Qt status fix: 'showexp'

Qt status fix: 'showexp'

For Qt, experience points weren't shown when enabling 'showexp'
option because they were conditional upon '#if EXP_ON_BOTL'.  That
got eliminated prior to 3.6.0 so wasn't defined for qt_stat.cpp.

When displayed, show Exp as Level:Xp/Exp instead of as a separate
status field.  This has the intentional side-effect of omitting it
when hero is polymorphed and status shows HD instead of Xp.

Label the six characteristics in mixed case instead of all upper
case:  Str, Dex, and so forth.