Add Unicode.Char.Case.Compat

[wismill]

Add Unicode.Char.Case.Compat with toLower, toUpper and toTitle functions.

Fix UnicodeData.txt parsing.

This fixes the missing functions for drop-in replacement of Data.Char (see #47).

[harendra-kumar]

I am wondering if we should have a single Unicode.Char.Compat module instead of multiple compat modules in order to reduce the number of modules.

[wismill]

I am wondering if we should have a single Unicode.Char.Compat module instead of multiple compat modules in order to reduce the number of modules.

I think this is the last Compat module; two of such modules seems reasonable.

[adithyaov]

Looks good!

[wismill]

I added benchmarks. We get a nice 3× speedup compared to base.