Adding TO_NUMBER built-in function and associated tests.  Function does not yet support format string.
Added end-to-end tests for TO_NUMBER, removed ToNumberParseNode, other minor cleanup suggested by @jtaylor
Merge pull request #73 from elilevine/master

Adding TO_NUMBER built-in function and associated tests.
Merge pull request #72 from tonyhuang/decimal

Rename getMaxLength to getByteSize