GitLab

* Movec ctags-related structs in ctags package

* Unified GCCPreprocRunner* functions

There is no need to duplicate a function that basically does the same
thing.

* Added implementation of functional algorithms

(until they are available in the golang standard library...)

* legacy: use generic algos where possibile

* Removed useless call to FilterSketchSource

* Converted AddPrototypes into a function