Start work on a usable specification

Pulled the contents of dlang.org/lex.html into the spec.
Convert the spec to use a custom BNF syntax.

Added the Universal Alpha data from the C99 specification.

Production Syntax Summary
 - .. indicates a contiguous series including its endpoints
 - | means disjunction (alternation)
 - white space between productions means conjunction
 - non-terminal productions begin with an upper-case letter
 - terminal string literals do not need to be quoted if beginning
   with a lower-case letter
 - a Unicode literal has the form U+dddd
 - +NonterminalProduction means one or many
 - +(...) means the same for more than one production
 - *NonterminalProduction means zero or many
 - *(...) means the same for more than one production
 - Number(...) means a certain number of
Added comments to the Puctuator production
Merge pull request #1 from joichiro/spec

Add a specification