add Benchmark tests and use strconv instead of fmt.Sprintf for ANSI construction

[thaJeztah]

• depends on / stacked on remove redundant init functions, update godoc, and add some consts #8

---

add benchmark tests

goos: darwin
goarch: arm64
pkg: github.com/morikuni/aec
cpu: Apple M3 Pro

BenchmarkCursor/0            940589062     1.072 ns/op    0 B/op    0 allocs/op
BenchmarkCursor/2             21112914    64.86 ns/op    20 B/op    2 allocs/op
BenchmarkCursor/20            18367920    70.76 ns/op    21 B/op    2 allocs/op
BenchmarkCursor/200           17084241    70.71 ns/op    24 B/op    2 allocs/op

BenchmarkPosition/0,0         13334660    91.47 ns/op    24 B/op    2 allocs/op
BenchmarkPosition/2,2         13352409    94.05 ns/op    24 B/op    2 allocs/op
BenchmarkPosition/20,20       12992484    94.37 ns/op    24 B/op    2 allocs/op
BenchmarkPosition/200,200     12199471   100.20 ns/op    32 B/op    2 allocs/op
BenchmarkPosition/5,15        12582919    96.98 ns/op    24 B/op    2 allocs/op

BenchmarkScrollUpDown/0      645249318     1.61 ns/op     0 B/op    0 allocs/op
BenchmarkScrollUpDown/2       17620928    69.66 ns/op    20 B/op    2 allocs/op
BenchmarkScrollUpDown/20      17966480    69.91 ns/op    21 B/op    2 allocs/op
BenchmarkScrollUpDown/200     16414399    73.58 ns/op    24 B/op    2 allocs/op

BenchmarkColor3BitF           13825933    83.02 ns/op    21 B/op    2 allocs/op
BenchmarkColor8BitF           13356769    92.91 ns/op    32 B/op    2 allocs/op
BenchmarkFullColorF            9991122   119.50 ns/op    40 B/op    2 allocs/op

PASS
ok   github.com/morikuni/aec    21.156s

use strconv instead of fmt.Sprintf for ANSI construction

Improve performance

goos: darwin
goarch: arm64
pkg: github.com/morikuni/aec
cpu: Apple M3 Pro
                 │  before.txt  │              after.txt              │
                 │    sec/op    │   sec/op     vs base                │
Cursor/0            1.069n ± 5%   1.073n ± 1%        ~ (p=0.402 n=10)
Cursor/2            68.69n ± 2%   28.66n ± 2%  -58.27% (p=0.000 n=10)
Cursor/20           70.09n ± 2%   29.11n ± 2%  -58.47% (p=0.000 n=10)
Cursor/200          72.99n ± 3%   31.43n ± 1%  -56.94% (p=0.000 n=10)
Position/0,0        94.25n ± 3%   12.59n ± 2%  -86.64% (p=0.000 n=10)
Position/2,2        94.14n ± 2%   31.20n ± 2%  -66.86% (p=0.000 n=10)
Position/20,20      93.38n ± 3%   29.48n ± 2%  -68.42% (p=0.000 n=10)
Position/200,200    97.97n ± 2%   36.22n ± 7%  -63.03% (p=0.000 n=10)
Position/5,15       96.52n ± 3%   32.36n ± 2%  -66.47% (p=0.000 n=10)
ScrollUpDown/0      1.669n ± 8%   1.101n ± 3%  -34.05% (p=0.000 n=10)
ScrollUpDown/2      69.02n ± 2%   30.17n ± 1%  -56.30% (p=0.000 n=10)
ScrollUpDown/20     69.69n ± 2%   31.35n ± 2%  -55.02% (p=0.000 n=10)
ScrollUpDown/200    73.78n ± 1%   32.23n ± 5%  -56.32% (p=0.000 n=10)
Color3BitF          88.47n ± 5%   30.39n ± 3%  -65.66% (p=0.000 n=10)
Color8BitF          85.81n ± 8%   34.33n ± 1%  -59.99% (p=0.000 n=10)
FullColorF         113.50n ± 2%   44.19n ± 1%  -61.07% (p=0.000 n=10)
geomean             49.95n        19.87n       -60.22%

                 │  before.txt  │              after.txt               │
                 │     B/op     │    B/op     vs base                  │
Cursor/0           0.000 ± 0%     0.000 ± 0%        ~ (p=1.000 n=10) ¹
Cursor/2           20.00 ± 0%     20.00 ± 0%        ~ (p=1.000 n=10) ¹
Cursor/20          21.00 ± 0%     21.00 ± 0%        ~ (p=1.000 n=10) ¹
Cursor/200         24.00 ± 0%     24.00 ± 0%        ~ (p=1.000 n=10) ¹
Position/0,0       24.00 ± 0%     16.00 ± 0%  -33.33% (p=0.000 n=10)
Position/2,2       24.00 ± 0%     24.00 ± 0%        ~ (p=1.000 n=10) ¹
Position/20,20     24.00 ± 0%     24.00 ± 0%        ~ (p=1.000 n=10) ¹
Position/200,200   32.00 ± 0%     32.00 ± 0%        ~ (p=1.000 n=10) ¹
Position/5,15      24.00 ± 0%     24.00 ± 0%        ~ (p=1.000 n=10) ¹
ScrollUpDown/0     0.000 ± 0%     0.000 ± 0%        ~ (p=1.000 n=10) ¹
ScrollUpDown/2     20.00 ± 0%     20.00 ± 0%        ~ (p=1.000 n=10) ¹
ScrollUpDown/20    21.00 ± 0%     21.00 ± 0%        ~ (p=1.000 n=10) ¹
ScrollUpDown/200   24.00 ± 0%     24.00 ± 0%        ~ (p=1.000 n=10) ¹
Color3BitF         21.00 ± 0%     21.00 ± 0%        ~ (p=1.000 n=10) ¹
Color8BitF         32.00 ± 0%     32.00 ± 0%        ~ (p=1.000 n=10) ¹
FullColorF         40.00 ± 0%     40.00 ± 0%        ~ (p=1.000 n=10) ¹
geomean                       ²                -2.50%                ²
¹ all samples are equal
² summaries must be >0 to compute geomean

                 │  before.txt  │              after.txt               │
                 │  allocs/op   │ allocs/op   vs base                  │
Cursor/0           0.000 ± 0%     0.000 ± 0%        ~ (p=1.000 n=10) ¹
Cursor/2           2.000 ± 0%     2.000 ± 0%        ~ (p=1.000 n=10) ¹
Cursor/20          2.000 ± 0%     2.000 ± 0%        ~ (p=1.000 n=10) ¹
Cursor/200         2.000 ± 0%     2.000 ± 0%        ~ (p=1.000 n=10) ¹
Position/0,0       2.000 ± 0%     1.000 ± 0%  -50.00% (p=0.000 n=10)
Position/2,2       2.000 ± 0%     2.000 ± 0%        ~ (p=1.000 n=10) ¹
Position/20,20     2.000 ± 0%     2.000 ± 0%        ~ (p=1.000 n=10) ¹
Position/200,200   2.000 ± 0%     2.000 ± 0%        ~ (p=1.000 n=10) ¹
Position/5,15      2.000 ± 0%     2.000 ± 0%        ~ (p=1.000 n=10) ¹
ScrollUpDown/0     0.000 ± 0%     0.000 ± 0%        ~ (p=1.000 n=10) ¹
ScrollUpDown/2     2.000 ± 0%     2.000 ± 0%        ~ (p=1.000 n=10) ¹
ScrollUpDown/20    2.000 ± 0%     2.000 ± 0%        ~ (p=1.000 n=10) ¹
ScrollUpDown/200   2.000 ± 0%     2.000 ± 0%        ~ (p=1.000 n=10) ¹
Color3BitF         2.000 ± 0%     2.000 ± 0%        ~ (p=1.000 n=10) ¹
Color8BitF         2.000 ± 0%     2.000 ± 0%        ~ (p=1.000 n=10) ¹
FullColorF         2.000 ± 0%     2.000 ± 0%        ~ (p=1.000 n=10) ¹
geomean                       ²                -4.24%                ²
¹ all samples are equal
² summaries must be >0 to compute geomean