Preparing for 6.0

[orbitalquark]

Scintillua 6.0 will be a major new release. Scintilla-based applications will need to be changed, as the Scintilla lexer was renamed, rewritten, and no longer performs its own styling -- editors are responsible for styling. From the initial changelog:

• Removed support for old legacy lexers.
• Rewrote Scintillua lexer to behave like a typical Scintilla lexer.
  • Renamed to Scintillua from LexLPeg.
  • Renamed lpeg.home library property to scintillua.lexers.
  • Removed lpeg.color.theme library property
  • CreateLexer() is the only way to load lexers now; no more private call API.
  • Removed all styling capability. Applications are responsible for setting styles.
  • Implemented ILexer5's NamedStyles() and NameOfStyles() so editors can construct style map.
  • Replaced Lua theme files with SciTE properties files in themes/ for demonstration.
  • Renamed fold.* properties to fold.scintillua.*.
  • Added GetCreateLexerError() function for fetching CreateLexer() errors.
• Replaced "token" concept with "tags".
• Deprecated lexer.token() in favor of lexer.tag() and made it an instance method.
• Dropped 32-bit Windows DLL support.
• Removed lexer.property_expanded.
• Compile a very minimal subset of Lua into Scintillua (no bit32, coroutine, debug, io, package, or os libraries).
• Applications can use their own keyword lists for lexers that support it.
• More restricted sandbox environment for lexers.
• All lexers created with lexer.new() have a default whitespace rule; deprecated
  lexer.WHITESPACE.
• Child lexers can extend their parent's keyword lists.
• Added more builtin tag/token names.
• All lexers created with lexer.new() have a default set of user word lists.

Scintillua 5 lexers are considered to be "new" legacy lexers and will eventually need to be migrated. They should mostly run without issue for now. Issue #76 tracks which lexers still need to be migrated.

These changes are now in the repository.