bump version
use str2nr to parse hex color code

here is a test script:
https://gist.github.com/UncleBill/9482014#file-gistfile2-vim
update "Thanks To"
two some tweaks

min() comparing to if-condition, has almost the same perfermance,(in
fact, min() is tiny faster than if-condition in most test cases), and
min() looks more clear
Only colorize visible area; remove a splith autocmd

Faster for large file
Code indent.