Add GameData methodmap

[peace-maker]

Wrap gamedata natives in a pretty methodmap and update stock plugins/includes to use it.

This fixes bad documentation on GameConfGetAddress and not closing the gameconfig file if handle creation fails as well.

[asherkin]

I'm not a fan of the name GameConf, but don't really have a better suggestion, opening up to the floor? @alliedmodders/sourcemod

Implementation looks sounds, nice catch on the fixes.

[peace-maker]

Could call it GameData since that's what people use to refer to it.

[Fyren]

I think with the existing natives named the way they are, I'd prefer GameConf.

[Headline]

Personally, I think that naming it GameData is a better choice even though it differs from the original native's naming scheme. It looks cleaner, and this is an evolving language anyway. 😛

I just wanted to give my two cents, if that's welcome.

[psychonic]

I have no strong feelings one way or the other on the naming. Everything else looks okay to me.

[Headline]

this lgtm; much cleaner and is a good addition to the mm api. 🥂