core: small performance improvements

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>
core: add API to lock the clipboards manager

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>

Conflicts:
	libgpaste/core/gpaste-clipboards-manager.c
keybinder: fix paste and pop

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>
gpasted: adapt to paste and pop changes

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>
silence warning

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>
version bump

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>