v1.2.0 Adds some features and fixes some bugs

Fix bug where NilChance(0) could stillresult in nil (#47)
Add customizable string generators
Optimize randBool() and randString() (#41)
Update import statement to reference correct library name (#40)
Add support to fuzz from go-fuzz input (#35)
Fix charRange to allow picking the last item (#36)
Implement fuzzing of complex types (#37)