[BUGFIX] Fixes parsing of single forward slash

Bug has been introduced when I changed the regular
expression for comments to the one of the w3c. I
previously had this clause baked inside the comment
regex. It should be cleaner and better to read now.
A forward slash is now a valid char for css, but we
ensure that any comment is parsed before this data.
Adds additional regular expressions for parsing
Adds framework for shorthand property parsing

Adds first implementation for padding and margin.
These modules are not loaded by default, if you want
these to be parsed you need to load the modules yourself.
* They are not do anything useful for now (just parsing).
Adds more complex shorthand implementation of font

Font shorthand has a more complex logic, specially with
the appearance of line-height after font-size (delimited)
by a forward slash.