Added layouts for Launchpad MK1 NOVLPD01 and MK3 Pro

[sslater11]

Added layouts for Launchpad MK1 & MK Pro 3.
MK1 works
MK2 & MK3 3 needs testing( tester is found for MK3, just waiting for them ). They both have the same layout for the 8x8 pads, but their controls are different and I've not added those.

We should probably move the layouts to a separate file.

I removed your code for your launchpad layout, because it just looks like the numbers increment and has way too many rows.

Made the reaimgui required message clearer, because I was googling REAL-m-gui, the capital i lead to confusion.

Made an array of midi values for each different launchpad model, instead of your for loop that generates the layout.

Changed layout magic numbers to variable names for easier to read code.

Changed the way the layouts drop down menu gets/sets the layout name/index

POSSIBLE BUG: I changed the indexes, so we need to change UI_drracklayout=1 in reaper-extstate.ini. User can fix it by clicking on the devices menu. the rack will just not show up at all until they choose a midi device.

Added a basic function to check if the layout is a launchpad or not.

[sslater11]

I found that the 8x8 pads layout for MK2 and MK3 are the same. It needs testing, but should work.
The control keys are different, but I've not worked on adding those yet.

I managed to get my lights lit up today so I'm going to play around with that :). I'm thinking the pad can light up whilst a sample is playing and turn off when it stops.

[MichaelPilyavskiy]

I added custom layout instead with ability to remap individual pads. Does that reduce need of efforts to build custom layout?