Improve possible compatibility

[Astralcircle]

Some addons can overwrite ent.OldColor with a non-color which causes errors like these:

[falcos-prop-protection-master] addons/falcos-prop-protection-master/lua/fpp/server/antispam.lua:9: attempt to index field 'OldColor' (a number value)
1. GhostFreeze - addons/falcos-prop-protection-master/lua/fpp/server/antispam.lua:9
 2. fn - addons/gmod_anticrash-main/lua/autorun/server/sv_anticrash_main.lua:47
  3. unknown - addons/ulib-master/lua/ulib/shared/hook.lua:109

[FPtje]

Thanks! Would it be an idea to rename OldColor to something like FPPOldColor? That way there would be no name conflict.

[Astralcircle]

This option would also be suitable

[FPtje]

Thanks! The code looks good. I will run it on my local computer to run some extra tests. It may take a couple of days before I have the time to do that, so apologies for the delay.

[FPtje]

It works as expected. Merging.
These addon incompatibilities are very hard for me to discover, so I very much appreciate the PR fixing it. Thank you for taking the effort to make a PR!

[FPtje]

The workshop, DarkRP and DarkRP's workshop have now also been updated with the fix 👍