support haxe final keyword

[romamik]

Support haxe final keyword for variable completion and coloring.
Resolves#2775 and partially resolves#1925 (does not support final as method modifier.)

[SlavaRa]

@romamik should this work under haxe < 4.0.0?

[romamik]

I did not test with older haxe versions. IMHO it should not break anything, but may display final in autocompletion list.

[SlavaRa]

I did not test with older haxe versions. IMHO it should not break anything, but may display final in autocompletion list.

I would not be so sure without the tests :)
This shouldn't work for versions < 4.0.0

[romamik]

Do you mean to enable/disable this code depending on haxe version? Is there some example of how can this be accomplished?

[romamik]

I've added version check. Now final is not shown in completion if haxe version is < 4. Also I've tested with haxe 3.4.7.

Not sure if the way I add/remove/check item existense in features.codeKeywords and features.declKeywords arrays is correct.

[SlavaRa]

@romamik i'll check and merge today.