Enhancement #233  -  Change Guide Colours

- Mainly copy&paste from "Change Grid Colors" commit 89ad460184f86a4427184aa0a6bf955b7648b987

- Seems to work better on parsing meta data (http://sourceforge.net/p/synfig/mailman/message/31421536/)
using std::vector and stringstream
- Send a message on status bar if guide_color not well formated
BuxFix on grid color load.

- Seems to work better on parsing meta data (http://sourceforge.net/p/synfig/mailman/message/31421536/)
using std::vector and stringstream
- Send a message on status bar if grid_color not well formated
Fix - Grid and Guide color, reject more than 3 parameters

- Add a test to do reject a string with more than 3 colors definition.