Add myargmalloc boolean to detect whether we allocated myargv ourselves or not, so we don't free myargv if we didn't

Fix servers disappearing from the server list when you refresh, by forcefully closing connnections to the servers immediately after sending ASKINFO. Also force close connections to old server list when refreshing, because we don't need to hear from them anymore full stop.

Fix the nonsense going on here regarding dc_colormap, this makes FOF walls appear strange if they were for a fog block with colormap adjacent to a normal sector with a colormap and no FOFs.

...that was a mouthful

Make sure GetMODVersion and its console equiv properly detect failing to get a reply from the MS, also added extra console/menu messages

Fix stringop-truncation: ‘strncpy’ output truncated before terminating nul copying 8 bytes from a string of the same length

Fix =sizeof-pointer-memaccess: argument to ‘sizeof’ in ‘strncpy’ call is the same expression as the source; did you mean to use the size of the destination?

Fix OpenGL's HUD not being scaled the same way as Software's, by removing an old OpenGL-specific hack for fdupx/fdupy

Split camera initialisation code from P_SetupLevel, make sure the camera has an initial subsector set!

Made some efforts to improve efficiency of new code, hard to tell if I've made it better or worse though honestly

R_IsEmptyLine is now a thing too btw

More progress, NEWCLIP added to doomdef.h, sadly it actually all lags the game so I've disabled it for now

Other notes:
* on second thought I'll keep the hw_clip functions' gld prefixes rather than HWR, not like it matters either way
* despite the extra lag it does fix the issues with translucent walls and such when displayed at different vertical angles, such as with the GFZ1 waterfall

Other notes:
* Renamed all new functions to have HWR_ prefix instead of gld_, for consistency
* HWR_FrustrumSetup and HWR_SphereInFrustum are disabled and require HAVE_SPHEREFRUSTRUM. This is because 1) SRB2CB did not need the code, so presumably neither will we, and 2) there are some OpenGL API functions used there that due to our way of using OpenGL we don't use outside of r_opengl.c, which makes dealing with HWR_FrustrumSetup complicated in theory
* The new clipping functions are not added to OpenGL's "main" rendering code itself just yet, they're just available to use now once hw_clip.h is included

* Move the misc types in the file to bottom, so that ATTRPACK at least is usable for RGBA_t
* Include endian.h, so that UINT2RGBA can be defined correctly for big endian builds
* Add more comments to make clear the main sections of the file

Remove FUNCMATH from functions with a void return value or args, or examine variables other than their args (which could be modified)