Merge branch 'hotfix/0.4.2'
Merge branch 'release/0.5'
Add tags to test
Swap formulas and results columns in editor
Update compatible up to WP 4.0
Remove session stuff to avoid openbasedir bug
Prefix screenhots by zeros
Update changelog and bump version to 0.5.1
Merge branch 'hotfix/0.5.1' into develop