Improving independency between batoms and batoms_api

[alchem0x2A]

Related to #5 . We should make the batoms main package and batoms_api as independent as possible. In a minimal content, we should allow user to:

1. Only install batoms_api in her / his working environment, while batoms and blender is managed in another environment
2. On the rendering part, only batoms is involved, no calls to batoms_api is needed

A possible solution is to add the script_api as a submodule of batoms which handles the .inp file through sys.argv, equivalent to

$BLENDER -b --python-expr "from batoms.script_api import run; run()" -- <path/to/.batoms.inp>

In this case, we can dump the schema dict into .batoms.inp, to avoid loading batoms_api and do version checking

[superstar54]

Yes, I agree. It's a good solution to add script_api into batoms, and use batoms for all the rendering parts. The batoms_api is only used for generating the input file for batoms and calling batoms to run the jobs.