cscope: only match one occurrence per token

For lines like
  go("gogogo")
we would export four function calls (one per "go") even though the extractor
correctly only reported the one.
cscope: work around for global function calls

Cscope refuses to recognize function calls that happen outside of a function
definition - this isn't an issue in C, but in ruby et al. it can be. Insert a
shim "global" function in places to work around this limitation.
add bug fixes to changelog
Merge pull request #44 from eapache/cscope-fixes

Cscope fixes