Huge commit incomming.  Hold onto your butts.

Removed extraneous code comments.
Added exsto.Debug holder function to exsto_init to allow for exsto.Debug
to be called pretty much anywhere now.
OnShowtime and OnBackstage now pass the page object.
Added var:SetCategory( cat ) to variables.
Started work on Exsto Settings page.
Switched variables from using (true,false) to (1,0) to make the convars
handle it easier.
'ExDebugLevel' variable now sets the level in which Exsto prints it
debug messages.
Fixed variables not properly checking possible values.
Removed sv_variables.  WARNING**** This is going to break shit.  Please
report!
Brought FEL's exsto extension up to speed in terms of hooks + code.  Now
properly integrates debug variables.
Added ExBooleanChoice and ExNumberChoice controls.