v0.8.0 - Identifier processor, Java 8 support and more tests

• Added IdentifierProcessor that searches for strings in identifiers and hands resulting matches to corresponding targets
• Added a base handler target, a replacing target and a throw target
• Moved a few things around in the packages
• Added tests for a few more classes and improved other tests, especially for new functionality
• Made ExtendedContext and the new ExtendedTerminalNode implement a new general-purpose tree node interface TreeMember
• The generated parser uses a custom superclass now that generates the new type of terminal nodes
• Changed the visibility of many TransformationPhase methods to be more restrictive
• Refactored how node replacement and removal works in TransformationPhase. It's now more generally useful and uses TreeMember.
• The dynamic parse tree walker removes placeholder nodes after finishing a child array now. This may make future walks more efficient and maybe reduces problems with pattern matching (not tested yet)
• Re-introduced StringNode which Directive now uses as it's superclass. String node can also be used for other purposes. (It's part of the AST node family)

Meta:

• Made glsl-transformer compatible with Java 8 by using jabel and adding a compatability utils class
• Updated ANTLR4 to 4.9.3

Full Changelog: v0.7.0...v0.8.0