Various fixes

[jirutka]

Here’s the second round.

Fix bad class method definitions

Good explanation is in the Ruby Style Guide.

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 subdirectory, to be very clear what's going on.

Remove unnecessary monkey-patching of String

Monkey-patching should be used very cautiously and sparingly, especially in the case of core classes. When you monkey-patch some class (e.g. add some method to it), it doesn’t change it only in the current context (file), but globally!

Fix camelCase method names

This is strong Ruby convention.

Remove unreasonable includes to main

I’m not sure if you actually know what include does. There’s a good explanation on StackOverflow. When you include some class/module on the top-level (i.e. not inside another class/module), then you include it into the top-level object called main. This is not scoped to the current file, it’s global! This is useful only for DSLs, in the most of other cases it’s inappropriate and messy.