Core/MMAPS: Fix invisible wall issue in MMAPS.

Fix invisible wall issues in MMAPS caused by tile connections not being extracted correctly.
This reverts aa645683b8b25bfb35cb977678daf5c56c1531e6 and restores an old version of recastnavigation, most likely https://github.com/memononen/recastnavigation/commit/1be9de72d87dcfdecf6bea30f5461745f7d7afe6 .

Re-extracting MMAPS is required.
Core/PlayerDump: fix mail items and gifts export
Scripts/Ulduar: Fix Algalon the Observer outro phase(fixes kill credit and some achieves).
DB/Creature: spawn Stabled Argent Warhorse

By Foldor, closes #11479, updates #11043
DB/Creature: Fix another trigger visible to players
DB/Creature: Delete some double spawns

Updates #1515
Merge remote-tracking branch 'upstream/master'