Improved Siren Mod 3.6

Fixed a bug that could cause a vehicle error on load

This is the 2nd part of the traffic update!
- Traffic now use the sirens of the mod instead of using default game's sirens.
- They randomly switch between the main siren and the rumblers (if there is any rumbler)
- They more often use the siren than the rumbler

- The mod now works with traffic
- Improved ram usage and performances

Fixed MS4000 rumblers

- Added MS4000 siren
- Improved performances
- Reduced ram usage

Added PA300 siren (misses one rumbler)

- Improved Galls Street Thunder siren
- Replaced blank warnings and horns by default ones

Fixed a bug with default vehicle having siren

Thanks to WarDaddyUSA for the report

- Added some fancy UI messages for better user experience
- Improved the Welen Epsilon siren
- Improved BeamMP compatibility
- Fixed some bugs