Languages.hcl terraform semantic highlights

[lkishalmi]

This change removes the mostly redundant TerraformLexer grammar, which added a few keywords of Terraform dialect of HCL.

The coloring is done by the real Terraform specific structure analyzer. There are room for improvements, especially when I'd finish the expression part of the AST, but let's do baby steps.

[lkishalmi]

So added a few features in the last commit:

• Added a group separator coloring option for {} and []
• Terraform Declaration blocks (I could not find the correct term for root level blocks) got recognized, their ID is bold now
• Terraform attribute names highlighted as fields
• Added Tabs and Insert formatting to the Options dialog, unfortunately does not really work without a formatter.
• Added code samples to the Options dialog

[lkishalmi]

[matthiasblaesing]

Looks sane to me.