[Bash] Strict special parameter highlighting

[zufuliu]

Current code treat all punctuation and white spaces as single character special parameter that will case bugs, like the one reported at zufuliu/notepad4#684:

*, @, #, ?, -, $, ! are supported in bash, zsh, dash, and ksh; tcsh adds% and < (highlight $< seems will cause other bug).

A simple fix is adding extra check after scalar has no delimiter pair comment:

// `setParam` will be replaced with `IsBashParameter()`.
if (!IsBashParameter(sc.chNext) && !IsSpecialParameter(sc.chNext)) {
	stylingInside = false;
}

lexilla/lexers/LexBash.cxx

Lines 362 to 368 in 5f0c215

	} else {
	// scalar has no delimiter pair
	}
	if (!stylingInside) {
	sc.ChangeState(state);
	} else {
	sc.ChangeState(sc.state | insideCommand);

[zufuliu]

Another fix is adding

const CharacterSet setParamStart(CharacterSet::setAlphaNum, "\'\"`{[(_*@#?-$!");

if (sc.ch == '$' && setParamStart.Contains(sc.chNext)) {
	QuoteStack.Expand(sc, cmdState, stylingInside);
	continue;	
}

so special parameter list could be configurable.

[nyamatongwe]

Since the different shells have different choices, using a CharacterSet that could be modified by options appears sensible to me.

[zufuliu]

The patch, added setParamStart into QuoteStackCls to avoid code duplication.
bash-param-0716.zip

[zufuliu]

Uploaded another fix at #186, which added property lexer.bash.special.parameter to set custom special parameters.