initial preperation, very riugh functionality
Fixed lexing for floats, ranges and integers.
removed `alias` and `mime type` form description
added web url to description
added encoding, languages and emoji in visualise
fixed nested comments
defined keywords as class methods, added constants
include all unicode chars, not most elegant solution
fixed bug which overrides CSharp lexer
fixed unicode to match swift syntax guide.

Some of the characters are not in Syntax Guide but do work in Playgrounds and
Xcode. I've included Georgian an Japanese in samples. Emojis work fine though.
whitespace fixes
kludge to get previews working for now
Merge branch 'master' into feature.swift
simplify the implementation of id

according to "soft" description in the spec, includes japanese and
georgian
add string interpolation and escapes
add better variable highlighting
Merge branch 'feature.swift'