Added global context
Removed unused deserialize_state_is_ready()
Removed unused serializer_yajl_state_free()
Integrate supertype of deserializer_state

This patch integrates the supertype of the `struct deserializer_state`
into the `struct deserializer_state` itself.
Integrate deserializer_state.{c,h} into other source files

(into deserializer_callbacks.{c,h} and deserializer.{c,h})
Integrate string_jump_state into deserializer callback code
Merge pull request #412 from matthiasbeyer/refactor-json_deserializer

Refactor JSON deserializer
Merge pull request #410 from TheNeikos/add-global_context

Added global context
Add command for overriding a stack position
Merge pull request #413 from matthiasbeyer/add-command_store

Add command for storing a value on a stack position
Fix: Add missing CMakeLists.txt entry for control command source file
Merge pull request #415 from matthiasbeyer/fix-missing_cmakelists_entry

Someone missed to add the CMakeLists.txt entry for the control.c file.
Added global context