Change Gosu version to GOSU-PERF-SNAPSHOT / 3.4.PERF-SNAPSHOT
Several bytecode/compiler performance improvements

- add (but not yet enable) Gosu Marker annotation for Gosu types compiled to
  bytecode
- make string concatenation fast, no longer calls into
  AdditiveExpression#evaluate() at runtime, uses StringBuilder and doesn't call
  into the type system at all
- fix erasure of structure type array
- tune AdditiveExpression bytecode to support big addition and mixed boxed
  addition without involving type sys etc.
- optimize mixed BigXxx addition
- handle Dimension addition directly in bytecode
- handle CharSequence and other types in string concat
- use entityaccess to determine if the type is a typekey
- optimize multiplication bytecode, only calls into type system when dynamic
  operands involved
- refactor expr compilation, introduce abstraction ArithmeticExpressionTransformer
  to share code
- optimize type-as expr some, more to go still
- optimize unary expr
- optimize relational expr
- optimize unary expr
- optimize type-as expr
- fix boxed dimension multiplication
- fix dimension multiplication
- delegate to ICoercionManager#makeStringFrom() for all specially handled
  types :(
- utilize stringbuilder return value of itself in concat compilation
- explicit handling of char[]
- fix Boolean typeas
- handle null coercion, depending on gosu  language-level
- cache namespace, otherwise potential hotspot
- optimize equality-expr
- more relational expr optimizations
- more type-as optimazations
- make IDimension and ISequenceable extend Comparable, makes good sense and aids
  in perf wrt Gosu relational/eq operators
- fix bridge method generation for indirectly implemented iface methods on
  superclass e.g., LengthDim.
- fix bigdecimal multiplication
Minor

Fixing formatting issue and adding _build in .gitignore
Adding the implicit conversion char -> String to the Gosu Spec
Change versions to 1-perfComp-SNAPSHOT / 3.4-perfComp-SNAPSHOT
Performance improvements

-caching javac compiler instance
-disabling annotation processing while parsing java files
Reintroducing our old Java 7 ANTLR parser.

The official Java parser accessible by the Java Compiler Tree API is too slow.
We will switch back to the official one once we move to Java 8. It is not worth
the effort to upgrade our Java parser.
Change versions to 1.X-SNAPSHOT / 3.X-SNAPSHOT
Merge branch 'master' into perf

Conflicts:
	idea-gosu-plugin/pom.xml
Change versions to 1.X-SNAPSHOT / 3.X-SNAPSHOT
Merge branch 'perfCompilation'
- fix erasure of structure type array
Change versions to 1-perf-SNAPSHOT / 3-perf-SNAPSHOT
Merge remote-tracking branch 'remotes/origin/master' into perf
Merge branch 'structuralFix'
Merge branch 'master' into gosu/spec/expressions
verify that an anonymous class cannot declare its own constructors.
Disallow duplicate classes as in "class A { class A {}}"
Rewrite Block/Function-to-Interface coercion to be compiled statically.  Eliminates dynamic runtime coercion (no gosu runtime/parsing) for this case when directly casting a block to an interface.
compile directly asymmetric equality comparison when operands are not dynamic