improve :tabgroup switch
improve :tabgroup switch

  * create a new tab when non-tabs in the group and non-apptabs.
  * completable the argument desn't begin from group's id.

mcarton/vimperator-labs,nullren/vimperator-labs,paretje/vimperator-labs,derenio/vimperator-labs,Quicksaver/vimperator-labs,seanmorton/vimperator-labs,derenio/vimperator-labs,Sheile/vimperator-labs,Evidlo/vimperator-labs,paretje/vimperator-labs,zklinger/vimperator-labs,nullren/vimperator-labs,Sheile/vimperator-labs,Evidlo/vimperator-labs,Quicksaver/vimperator-labs,airodactyl/airodactyl,stemar94/vimperator-labs,mcarton/vimperator-labs,seanmorton/vimperator-labs,airodactyl/airodactyl,stemar94/vimperator-labs,zklinger/vimperator-labs