cosmetics
fixed PY-14488 Pycharm community 4 terminates with exception after installing and importing setting from old one
Merge remote-tracking branch 'origin/master'
external build: include module name into error message about missing Maven configuration
external build: corrected check for duplicated classes
removed dependency on RefResolveService live instance
Add several methods to convert JSON literals to Java values

* JsonStringLiteral#getValue returns escaped content of the string
with quotes stripped
* JsonBooleanLiteral#getValue returns true/false
* JsonNumberLiteral#getValue returns corresponding floating
point number

Also I removed some redundant accessors from API of elements.