Add Master IPC handler get_top_runner

Signed-off-by: Jiří Janoušek <janousek.jiri@gmail.com>
Ctl: query for top runner when -a not specified

Signed-off-by: Jiří Janoušek <janousek.jiri@gmail.com>
Add mapping of virtual modifiers to keybinder

It fixes Super+x keybindings etc.

Signed-off-by: Jiří Janoušek <janousek.jiri@gmail.com>
Add XKeyGrabberto manage x11 key grabbing

Signed-off-by: Jiří Janoušek <janousek.jiri@gmail.com>
Refactor GlobalKeybindings to multiple classes

Part of transition to shared global keybindings management in the master
process instead of individual grabbing in runner processes.

Signed-off-by: Jiří Janoušek <janousek.jiri@gmail.com>