Fix bad class method definitions
Move colored_text to core_ext subdir and rename to colored_string

There's a good convention to put monkey-patching of core classes into
core_ext directory, to be very clear what's going on.
Remove unnecessary monkey-patching of String
Remove unused String methods #eos and #whack
Fix camelCase method names
Remove unreasonable includes to main
Merge pull request #2 from jirutka/patch-3

Various fixes