Specify the ANSI pattern a little more

Since ANSI colours can only contain numbers and semi-colons, this will prevent
us from catchin a too wide array of things. For instance MXP tags could have
matched the regex, if there was a colour code somewhere after it.
Fix off by 1 bug

Indexed lua tables go from 1 to #table... So we need to include #t in the while
loop.
No bright colours for backgrounds

ANSI defines "bright" ambigously. Most terminals and most importantly mudlets
telnet parsing apply bright only to foreground colours. We stay consistent and
do the same.