Replace all remaining PNG icons by scalable ones and license details

edit_cut.svg: released under public domain by The Tango Desktop Project.
 https://commons.wikimedia.org/wiki/File:Edit-cut.svg

hourglass.svg: from Noto project, released under Apache license. See:
 https://commons.wikimedia.org/wiki/File:Noto_Emoji_Pie_23f3.svg

Remaining ones are from https://codefisher.org/pastel-svg/
see details in `LICENSE-PLUGINS`

package_rename.svg, package_save.svg, clear_sorting.svg and script_copy.svg
are own work based on Pastel SVG and released under the same license.

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.