Replace wxRegex bindings for lua with boost::regex bindings

API is mostly unchanged other than the addition of a lot more flags.
Should be less buggy since it has an actual test suite, and generally
has a more powerful regex syntax with better support for Unicode.

The bindings are written in MoonScript. For now the compiled form is
store in the repo for convenince.
Make Lua 5.1 a required dependency
Drop support for non-UTF-8 lua scripts
Remove the charset detection from TextFileReader since it's never used
Remove the use of wxRegex for case-insensitive filtering
Build wx without wxRegex
Disable a pile of wx things we don't use
Select the right things in the select overlaps macro. Closes #1594.
Do a better job of picking a new active line after deleting lines

Set it to the first line not part of the selection after the selection
begins if there are any, and the last line remaining in the file if not
(i.e. the last line before the selection).

Closes #1595.
Report a more useful line number for bad lines in the TPP. Closes #1596.
Shuffle some stuff around in MicroDVDSubtitleFormat::ReadFile