SylkParser bug fixes

[speige]

Make SylkParser more robust to handle malformed files & ignore useless tags, like formatting.

[Drake53]

Do you have example .slk files which use these tags? I know the implementation is incomplete because I only intended to load the .slk files from wc3, which only use the ID, B, C, and E tags.

[speige]

SLK Files.zip
These are all files that are part of the base game extracted from the casc. They fail with the old SylkParser but work with the new version.

I can also get you examples from custom maps, if needed.

[Drake53]

Sorry it took a while to respond, the SLK project is not very high on my priority list (I would've prefered to not have this library at all since it's not really specific to wc3, but I couldn't find an existing package at the time). The diff is a bit hard to read since you refactored it quite a bit, so I made a separate PR (#76) with just the fix for reading a C line which has Y instead of X. I'm sure the class could use some perf improvements and refactoring, but I prefer to keep those efforts separate from bugfixes.