Remove unnecessary Struct.

There's already an initialization method with the default parameter for the options argument.
Use struct for the rules class.

The initialization method allows to use the struct.
Use delegators for some private methods in the rules class.
Wrap the rules class into the proper namespace.
Move redundant requiring forwardable module into the main class.
Move the parsed html reader into the private scope.
Use struct for the color class.

The initialization method allows to use the struct.
Inline the parse color method - it's not worth having the method.
Fix problem with the font tag which has both color & size attributes.

Previously the parser returned just the size bbcode tag instead of both - size & color.
Version bump to 1.0.1
Regenerate gemspec for version 1.0.1