Add home button to filesystem browser (closes #13)

This commit also gets rid of code duplication previously used when
adding the buttons to the filesystem browser's toolbar.

Signed-off-by: Niklas Koep <niklas.koep@gmail.com>
Expand ~ in filesystem browser

Signed-off-by: Niklas Koep <niklas.koep@gmail.com>
Forbid "send to current playlist" on filtered list

Signed-off-by: Niklas Koep <niklas.koep@gmail.com>
Fix regression with reaching the end of a playlist

The playlist rewrite introduced a regression which would not emit a
signal when there were no more items left to play in a playlist. This
means the player never transitioned to the stopped state by itself
anymore. This commit closes #11.

Signed-off-by: Niklas Koep <niklas.koep@gmail.com>
Rename BlaPlayer's seek signal to seeked

Additionally, emit the new position in the stream as parameter.

Signed-off-by: Niklas Koep <niklas.koep@gmail.com>
Add get_state_string() method to BlaPlayer

Signed-off-by: Niklas Koep <niklas.koep@gmail.com>
Add basic MPRIS2 support

Signed-off-by: Niklas Koep <niklas.koep@gmail.com>