0.3.7

Webmon 0.3.7: memory clean-ups spread over frames

• A clean-up no longer stops the game for up to a second: it advances Lua's
  incremental collector for a quarter of each frame's time (4-30 ms) until
  a fresh cycle has finished, finishing in one go only after 8 s; near the
  critical level a full clean-up still runs at once
• Log: clean-ups report their work time and how long they took
• Bridge test models the collector: backoff, spread clean-ups in a voxel
  town, critical full clean-ups