Bitmap: Don't unbind shader after render op

Since all rendering is now shader based, there's normally
no reason to ever unbind a shader program.
debugwriter.h: Use std::newl instead of '\n'
Graphics: Don't unbind shader
GLState: Add bound shader program to managed state

Squishes a handful of redundant binds per frame.
README: Mention cmake and fix some wording
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Revert "Font: Adhere to spec and set Font.default_name to "MS PGothic""

This reverts commit c9423164d48b4a383b046873a883e6242fe98825.

Turns out the spec was not adjusted correctly for the
English RGSS version; the de facto default is "Arial"
after all.