Add SourceBuffer class
Add ErrorLevel enum class
Add NeedMoreSource exception class
Add Reparse exception class
Add language::parser::Environment abstract class
Add language::parser::BasicEnvironment abstract class
Add Parser abstract class
Add Predicate type alias
Add LineContinuationTreatment enum class
Add Skipper class
Add WordComponentParser abstract class
Add RawStringParser class
Add WordParserImpl template class
Add WordParser class
Add CommentSkipper class
Add CommandParser abstract class
WIP: Add SimpleCommandParser class