Attempt to implement vadi2/mudlet-lua#8

Colours 10-17 are still missing and no testing was done yet.
More changes to ansi2decho

- fix the last commit
- add support for "light" or "bold" flag
- use rex.gsub instead of string.gsub. That way we can match the escape
  character
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.
Add first unit tests for ansi2echo()

These tests are simple, but add a first framework for further tests.
Run the correct unittest file for GUIUtils
Use tables instead of strings for colours

This way we don't need to unassemble and reassemble strings in convertindex.
Change the standard white to the default colour
Extend the test of single tags
Add more unittests for ansi2decho.
Add tests for xterm256 in ansi2decho()
Add some real life examples for ansi2decho tests
Merge pull request #10 from keneanung/master

Changes to ansi2decho