Add back -textmode command line option with but restrictions

[CosmicStar98]

Details

Support for this feature was recently removed but it would be nice for developers if it could make a return as long as it would be restricted to localhost servers in addition to a convar titled "sv_allowtextmode" which should be exclusive to offline mode servers in order to prevent future abuse of the feature.

Basic Context

Text mode was a command line launch option which clients could apply to have a bare metal Garry's Mod experience without any additional festivities like 3D rendering, sound processing, graphical interfaces, etc. quite literally a terminal interface.
It was an ideal utility for quickly testing code and could be a trivial task to apply automation for more complex scenarios or rigorous feature testing on the client side of things...

[artemking4]

you know you can still force it on yourself right

[gonzalologorg]

I think the main problem is spoofing your text mode client as a normal client, not the other way

I never had to use text mode, but sucks it's got taken away, thanks to shitty people

[Glebux]

I think leysourceengineclient is what you're looking for in this case.

[Yogpod]

https://commits.facepunch.com/508636
"Disable -textmode harder"