Added a method which allows to retrieve a specific variable value.
Added an argument which allows to disable "bubbling" (automatic search for the variable in a parent context until the query either hits the global namespace or a sandboxed environment).
Added throws declaration.
Added a method to allow modifying a variable in current context.
Allowed checking for variables in current context.
Enabled context tree recursion by default.
Added a parameter to allow modification of a variable in it's original context.
Fixed return value ...