A fast CSS selector engine and matcher

This release has correction/fixes for the following behaviours:

• several performance improvements and code clean up
• accepts and correctly resolves single character attribute names
• allow syntax parsing of :after, :before and other pseudo-elements
• added a shunt flag to also mute logging of errors/warnings to the console
• added support for escaped numbers & characters in CSS identifiers (v1.3.9)
• fix :not() negation pseudo-class containing nested pseudo-classes (v1.3.8)
• fix long invalid selectors can cause match() to hang forever (v1.3.7)
• fix incorrect regular expression pattern for combinators issue (v1.3.7)