Lexer clean up and refactor

- Added JSONPathToken class as value object
- Updated the lexing and filtering of the recursive token ("..") to allow for a combination of recursion
   and filters, eg. $..[?(@.type == 'suburb')].name

Merge pull request FlowCommunications#5 from twistor/fix-simple-access

Fix simple key usage (expressions are not required to start with "."). Allow expressions to start with "0". Move expression sanitizing to lexer.

Better empty/null checks for first and last methods

Fixing first & last methods

Removing .idea from repo

Merge branch 'master' of git://github.com/FlowCommunications/JSONPath

Added ArrayAccess and Iterator features to JSONPath;

JSONPath::find() method now returns new JSONPath objects with the filtered data for further iteration and chaining;
JSONPath::first() and ::last() methods no longer perform a query but return values from the current data collection;

Adding support for square bracket notation within query matches; Remo…

…ving regex log from parseExpressions to handle opening and closing brackets;

Initial commit