Title: Complex renaming
Goal: Rename functions with name gfun to sfun.
Parameters: [{module, test},{funname,gfun},{name,sfun}].
Documentation: There are more than one functions with name sfun in
 the file (they have different arity). Some of them have multiple
 function heads. Some of the gfun functions are exported, but there
 are also ones, which are not. The test file contains other functions
 (exported and not exported ones) with names different from gfun. 
