Templating engine

[lofcz]

This PR is here to track the progress on templating engine.
Spec: https://github.com/WattleScript/wattlescript/wiki/razor_like_templating_proposal

Escaping

• @@ escape

Implicit transitions

• calls
• access/indexing
• if
• else if
• elseif
• else
• for
• while
• do..while
• custom directives
• top level annotations? no viable syntax found, declare in a block @{}
• require
• function
• class
• mixin
• enum

Explicit transitions

• @()

Blocks

• @{}
• line transition @:
• preprocessor transition @#
• html transition
• <text> transition

Comments

• @* *@

Html encoding

• raw
• encode

Tests / parser functionality

• assert no input can hardlock the parser (infinite loop) added loop detector, we crash if something goes off
• report incorrect closing tags <div></divv> hard to do reliably. We crash where we can't recover instead.
• let parser enter recovery mode after an error
• cover more cases with HTML comments
• handle implicit closing of tags in terse mode <p>, <tr>, <td>... W3 spec
• parse attributes with understanding of content, report errors in attributes
• support <!div> notation to force plain element over taghelper
• report errors on implicit transitions via banned keywords else, elseif, else if
• sometimes BLOCK with empty content is emmited, discard
• add real world test cases
• test foreign html elements (svg, mathex..)
• make the tests pass on unix
• emit #line in debug mode
• self contained export