Fixed weird script tag behaviour and changed id/class highlighting

[jordanschalm]

• Changed the script tag regex so that open and closing parens are also highlighted, they were treated as regular text before.
• Added highlighting support for if/else statements that aren't part of an embedded javascript section
• Changed the highlighting of .something classes and #something-else IDs so that it is consistent with the built-in CSS highlighting rules (classes are treated as entities and IDs are treated as variables, which isn't really very descriptive but is far more useful when trying to see what's going on at a glance)

@tjholowaychuk