build: don't link core with x11

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>
GPasteItem: add method to get size

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

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

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>
GpasteHistory: track biggest item + size

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>
GPasteHistory: don't track active item as biggest

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>
GPasteHistory: elect biggest when loading

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>
GPasteImageItem: size is different when inactive

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>
GPasteHistory: always reelect when biggest goes off

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>
add new setting for max memory usage

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

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