UDMF linedef executor delay

Implements the executordelay linedef field for UDMF for delaying linedef executors. Replaces the Upper Unpegged + back sector height method used by the binary format. The delay can be changed at runtime with the new linedef type 465.

Test files:

• srb2win-executordelay.exe
• executordelay.wad

added 27 commits

• a881662c...6e7373a4 - 26 commits from branch udmf-next
• d3ec12c8 - Merge branch 'udmf-next' into executordelay

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added 64 commits

• d3ec12c8...1ccda0b8 - 63 commits from branch udmf-next
• ff3768f3 - Merge branch 'udmf-next' into executordelay

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changed the description

merged

mentioned in commit 11493e61