v2.8.0-pre9

• #278 Added possibility to easily react to button press-down only and ignore button release (without affecting feedback)
• #129 Added possibility to easily react to encoder increments or decrements only
• #279 Added possibility to let the target track depend on the current position of this ReaLearn track by making variable this_track_index available in the <Dynamic> track expression
• #277 Improved "Global: Set automation override" target by adding "None" option
• #277 Improved "Project: Invoke transport action" target by making "Play/stop" and "Play/pause" retriggerable
• #276 Fixed <Dynamic> expression evaluation by doing rounding (was sometimes leading to unexpected results because decimal digits were just being cut off)