Documentation

- Updated DEVELOPER docs regarding unit tests and the use of the 'needsTest'
  label in the bug database.
Lexer

- Renamed ::split to ::word_split, for clarity and because of the need for a
  full token split, coming next.
Lexer

- Implemented ::token_split, which performs a full lex, and doesn't require
  white space like ::word_split does.
- Added unit tests.
Parser

- Implemented ::capture_last, so that new args can be injected at either end
  of the command line.
Parser

- Modified ::injectDefault to use Lexer::token_split instead of
  Lexer::word_split which allows stranger default commands. Not sure if this
  is necessary, but it seems like the right thing.
CmdCustom

- Now places ( ) around the custom report filter. This gives it a chance at
  allowing 'or' and 'xor' operators when combined with a command lne filter.
Parser

- ::findPlainArgs will now only upgrade an arg to a search if the arg itself
  cannot be lexed into subtokens.