Correct engine (#11)

* fix: move 'array_buffer_allocator' variable into 'NodeEngine' class

* make only one global object and context for one engine, fix error on second script launch on the same engine

* debugger: fix debugger failure when passing commands with non-latin symbols (#10)

* fix: fix debugger disconnect after setting a breakpoint in file with non-latin name

* change Client.buffer type to Buffer

* fix

* add get version functions

* fix error when JS exception is thrown inside delphi callback (#12)

* fix: move 'array_buffer_allocator' variable into 'NodeEngine' class

* make only one global object and context for one engine, fix error on second script launch on the same engine

* Feat: add "SetInactive" function to stop handling callbacks; refactor delphi callbacks

* Feat: add variables and calling JS function without parameters