Wall-Jump. Continuation!

This is a fork of the Wall-Jump! mod. The original mod is available here: https://www.curseforge.com/minecraft/mc-mods/wall-jump

List of changes:
- Fixed an abuse (legal cheat), the essence of which is to completely avoid falling damage by double jumping close to the surface.
Now, to double jump in the air, player either must not fall, or must move fast enough along the X/Z axes. The values can be changed in the config.
- Added an icon notifying the player that he is falling and cannot double jump. Can be disabled in the config.
- Updated build.gradle.

I will not update this fork for modern versions of Minecraft. Such requests will be ignored.