Replace sidebar with tabs
Fix conflicting state (#13)
Fix NoneType has no attribute 'data' (#16)

Block signals when updating tables to slots don't try to process empty
rows, which of course, don't contain items.
Fix error deleting exercise (#19)
Create session outside of business logic (#20)

The session and its error handling is managed outside the code that uses
the session. As sessions are closed after being used, which is
currently always after a single transaction, the code looks strange (see
issue #25).
Fix merge using ours
Show message when no exercises exist (#23)
Add title to exercise dialog (#17)
Update sets table after deleting an exercise (#22)
Update sets table when last workout deleted (#24)
Update set list after editing exercise (#18)
Disable toolbar buttons when tables are empty (#26)
Remove redundent code
Bump version to 0.1.1
Merge branch 'release-0.1.1'