Added a bunch of String manipulation functions as per #18:
https://github.com/go-easygen/easygen/blob/8022ae39b5b2aa9001f159eeabaa82c7d010474d/t_strings_test.go#L35-L171
The actual reason creating this release is to warn people that the command-line replacing options will be removed in near future, ref #19.
If it is a concern to you, please discuss it in #19, else, it'll be remove in two or three weeks.
