Rework cli

[tDwtp]

Please note: I had to export (or hide) certain symbols:

• gravity_json.h (required) these are used mutliple times inside different exposed functions, some even beeing essential.
• gravity_utils.h (optional and handy) these are really handy for expanding gravity and are simple to understand.
• gravity_debug.h (optional) for (custom/gravity-specific) editors these symbols will come in handy ~~
• gravity_compiler.h#gravity_compiler_ast I dont think you wanted me to export that much, this would require gravity_token.h and gravity_node.h to be (maybe) mostly exposed to make any sense of it. Subsequently there would be more headers. I chose to hide it, as it is not used anywhere.

Regarding gravity_vm_register_args: I would expose optionals only for the dll (please evaluate this). but for the executable it would not make any sense. besides this is a little less dependent on the optionals. The call does not seem to do anything which requires this specific optional anyway? Maybe it should be moved to gravity_vm.h/*.c

I added Build-Targets and cleaned up the exports. I also want to add a dyn folder for the dynamically linkable libraries... currently it looks cluttered.

Also: we should export the computed_property_*/convert_value2* functions. They are really helpful and a headder should either have alle symbols exported or none.

SOMETHING needs to be bundled with the executable to make expansion possible. a *.lib/lib*.a is the absolute minimum. You have to die one death. headers should also be included. however... on windows a dllimport is needed. Thats why I created the gravity_common.h header. We can choose to put it there. (also it makes exported symbols not include gravity_value...)