Initial LLVM commit
Massive fixes. Works with LLVM 3.2
LLVMEvaluator example
minor fixes
Made variable access read directly from the map, rather than requiring a lookup. Added mutex
Updated examples and unit tests to new syntax
Updated README
Was deleting the wrong part of the llvm JIT. Have to remove the engine, which takes the rest with it. This fixes a massive memory leak
Added LLVMEvaluator for compiling optimised expressions.
Changed API usage, evaluator can only be given a single AST to evaluate.