Correct error handling in sceFontGet*Info().

And tone down the logging a bit.
Simplify the font code a tiny bit.
Don't pass quite so many args to DrawCharacter().
Clean up error codes in sceFontGetCharGlyphImage().
Check a potential crash in sceFontOpen().
Optimize alpha-only CLUTs, common for fonts.

This optimizes the case where fonts are drawn using animation (common in
RPGs, for example), and textures have to be decoded over and over.

Could probably be faster with SIMD.
Improve GPU invalidation interface, check fonts.

When a font is rendered, tell the GPU about it, but don't rehash.

This not only improves perf (less hashing) but makes font changes more
immediate (no deferred hashing.)  But only if they use sceFont.
Merge pull request #1694 from unknownbrackets/font-fix

Match PSP error behavior in some sceFont functions