updated readme

uses fenestro if in path & expects filename as param

fenestra->fenestro

added a comment

now escapes < & > in case we're diffing HTML

line numbers now monospaced

used different dwdiff flags which let me delete much cruft

tempfile deletion: fixed bug & made optional

moved svg icon into separate file

fixed re new dwdiff output

added a LICENSE.md file

Fenestro integration is now optional and documented

added some end curlys to javascript

unchanged background color now spans full width

removed "chrome" & integrated toggle with file name