Add `ccms freeze`

[keanuplayz]

pip freeze > requirements.txt appends all your Python project dependencies to a file called requirements.txt.
pip then allows you to install those dependencies with pip install -r requirements.txt.

I have an idea which seems interesting and handy to many developers and/or users.
ccms freeze > mods.txt.
This argument will scan your installed mods, and write them to a file.

The format of this file would be:

modname==0.17
modname2==2.3.3

You can then install all those mods with ccms install --file mods.txt

Issue with this is the lack of support for downgrading.

One solution would be to only output the names of the mods.

[keanuplayz]

Downgrading could be done manually. (e.g. changing the version number in your requirements file)
Only outputting the names would remove the capability of controlling the specific versions you would like to install.
Keeping version numbers would allow downgrading, since you can manually change version numbers yourself.