DB Schema: drag & drop SELECT queries

New check option in the contextual menu of the DB schema dock to allow
drag & drop of SELECT queries, provided that only a table or fields of
the same table are dragged from the DB Schema tree.

DB Browser for SQLite 3.12.2

DB Browser for SQLite 3.12.1

Simpler version for AppImage and branch name in the continuous release

The command `git rev-parse --abbrev-ref HEAD` is not returning the branch name
in the travis server, and for the version in AppImage filename it would be
enough to have the short commit id.

Note that these changes are branch dependant.

See issue sqlitebrowser#1092

Remover unused reference to the master branch

This command is failing

Update Arabic translation (sqlitebrowser#2406)

sqlitebrowser#2405
# Conflicts:
#	src/translations/sqlb_ar_SA.ts

DB Browser for SQLite 3.12.0

Update version number for 3.12.0

Updating version number for 3.12.0-rc1

We're using 3.11.300 for the 3.12.0-rc1, in order to keep
numerically lower than 3.12.0, which will be used for the
actual release.

Only include the build date for nightly builds.

Our alpha and beta releases use patch numbers greater than 99, so
were being caught by the version string check.