Advanced column builder

[Andriy Zhdanov]

Separate screen for defining system wide columns, using text area with code editing support (e.g. http://ace.c9.io/) and variable number of expressions (variables used in template).

Expressions could support code completion based on issue JSON.

Correspondingly, column dialog should transform into column popup to simply add/replace column in the search view.

[Andriy Zhdanov]

Column dialog is significantly improved:

• issue json to make it easier to write column expression, with http://highlightjs.org/
• preview based on selected issue
• initial code completion with http://codemirror.net/ for template and expression
  • todo: suggest available filters after pipe (|) in expression
  • todo: expression completion in template after opening double braces or inside double braces
  • todo: fix ESC not to close dialog when suggestions are open (now dialog closing on ESC is disabled)

Additionally, it should be possible to define angular filters.

[Andriy Zhdanov]

Additional improvements to be done when needed.