A style-sheet containing the string "url( )" with 1 or more characters of
whitespace in between the parentheses triggered an assertion failure in
scan_css_token.
scan_css_token would find the left parenthesis, find the right parenthesis,
and then scan forwards from the left parenthesis for a non-whitespace
character to find the start of the URL and backwards from the right
parenthesis to find the end of the URL. If there were whitespace and
nothing else, the start would be past the end, the routine would compute a
negative length for the URL, and then the routine would trigger an
assertion failure. Now the routine simply enforces a lower bound of length
0 for the URL.
This changes the init target to be idempotent: most importantly it will now
never overwrite a Makefile if it exists. Additionally 'make init' will
generate the .vimrc files. Yay, no more stupid 'added fairies' commits! ;)
