[qScriptEd] Evaluate FastColoredTextBox dependency

[DCxDemo]

Evaluate the necessity of FastColoredTextBox. Added this one in hopes to implement some fancy syntax highlighting, turned out to be useless feature, since ended up using np++ most of the times anyway. Also it was bugged and i had to include source to fix the bug instead of using nuget package. I don't quite remember if plain textbox didnt have some performance issues too, cause could be another reason for it. One more thing is FCTB doesn't allow tabs at all, forces spaces.