Expose command line and CAM information to web interface

[Jalle19]

This PR consists of four distinct parts:

• Extracting the API related functions to a separate module (symbols, variables). Now that it's separated it's easier to potentially refactor it in the future (e.g. the bandwidth handling still has some nasty cross-dependencies between modules).
• Exposing CAM information via new "symbols". I figured it's better to use a separate symbol array for these since CA support can be disabled at compile-time.
• Storing and exposing the command-line used to start the application
• Updating the web interface to expose the newly added information

I haven't been able to runtime test the CA changes yet, only modified the state locally in the web interface to emulate a CI device.

Screenshots:

When compile testing this on a different computer (with GCC 10 instead of GCC 9) I noticed that the GCC 10 complains about multiple definitions of variables by default (https://gcc.gnu.org/gcc-10/porting_to.html), so I figured I'd add the -fno-common option to Makefile.

Closes #981, closes #982

[Jalle19]

AFAICT I fixed Coverity CID 400978.

[Jalle19]

@catalinii ready for review

[Jalle19]

Added tests for get_command_line_string

[Jalle19]

Still need to find some time to test this before merging.

[Jalle19]

@pannlala found some use for your reader after all!

@catalinii turns out the logic that saved which CAIDs each CAM supports was broken. It's fixed in the latest commit.

Normal operation (no -c parameter):

Using -c to limit the list of supported CAIDs (-c 1:1-0100-0500):

[catalinii]

Please squash the commit that is merged when merging for the history to be cleaner.

[Jalle19]

Will do next time!