@-code expansion in text lines. Text searching for sub-board, group, or all.

Version 1.44:
Removed the scanScopePromptText text line and used the SubGroupOrAll line (621) from text.dat instead.  Also, the reader now supports @-code expansion in configured text strings.  This addresses issue #316 from Vincent Macaluso.
Text search now can search sub-board, group, or all like the other text searching (requested by Nelgin).
When reading the theme file, color settings are now checked to ensure they only have Synchronet attribute codes.