Enable jump to tag without activating a session

[mrkkrp]

I only activate session when I need to use REPL. Why jumping to a tag cannot work without this? hasktags gererates TAGS file, just read it and jump? No?

[gracjan]

Misarchitecture. Haskell mode checks if session exists so that it can use it to jump to definitions better. Checking if sessions exists has this side effect of starting a session. Somebody needs to fix this.