grammar: replace tabs with 4 spaces each and realign where necessary
grammar: use *, +, and ? quantifiers, indent grammar, and use regexes for token patterns, noting edge cases
grammar: match indentation across operators as well
grammar: clear up issues with leading 0's in token definitions
grammar: fix if-statement (translation used incorrect precedence of sequencing vs. alternation)
grammar: revert if-statement to original definition
Merge pull request #17 from mattfenwick/grammar2

Improved the description of the formal grammar