Add options to uppercase only certain keywords

[arturbalabanov]

We can divide the keywords into several groups -- types, functions, regular keywords etc.

A config option will be added to let the user specify the groups to be capitalised. By default it be set to all groups.

If a user sets the option to, say, ['keywords', 'types'], in, create and int would be capitalised but not count and sum since they belong in the 'functions' group.

[jsborjesson]

Better late than never! It seems reasonable to me, I would accept a change for this