Version 1.5.0 : many improvements, bug fixes, and Russian translation

Gameplay : Modified speed values for many shots : they used to decrease on short distance shots to make sure the ball would clear the net. Now that it is handled automatically on safe shots, this is not needed anymore, and speed values aren't linked to distance any more.
Gameplay : Added double tap slice. Second tap will make the shot and closer to the net, and a little faster.
Gameplay : Added thumbnail view of ball bounce on challenges from player POV.
Gameplay : Added possibility to cancel a shot by hitting any of the prepare buttons before ball impact.
Animations : Improved some running animations.
Online : Added sound effect when being invited to an online game.
Sound modding : Allowed variations on many sounds, such as bounce_xx.ogg, app1_xx.ogg, app3_xx.ogg, net_xx.ogg, etc...
Interface : Limited memory usage for player pictures in player selection menus.
Interface : Added Russian translation.
Bug fix : Fixed crash in editor when a modded anim is not available any more.
Bug fix : Removed incorrect triggering of grunt sounds on volleys, dropshots and lobs.
Bug fix : Removed incorrect display of aiming target in certain situations.