Problem: When setting the cterm background with ":hi Normal" the value of
'background' may be set wrongly.
Solution: Check that the color is less than 16. Don't set 'background' when
it was set explicitly. (Lemonboy, closes#1710)
Problem: Getting name of cleared highlight group is wrong. (Matt Wozniski)
Solution: Only skip over cleared names for completion. (closes#1592)
Also fix that a cleared group causes duplicate completions.
Problem: Some syntax arguments take effect even after "if 0". (Taylor
Venable)
Solution: Properly skip the syntax statements. Make "syn case" and "syn
conceal" report the current state. Fix that "syn clear" didn't
reset the conceal flag. Add tests for :syntax skipping properly.
Problem: When 'filetype' was set and reloading a buffer which does not
cause it to be set, the syntax isn't loaded. (KillTheMule)
Solution: Remember whether the FileType event was fired and fire it if not.
(Anton Lindqvist, closes#747)
