Prepare OpenREM for multilingual interface

[Ed McDonagh]

See the Django docs on internationalization and translation.

In summary, I think the task is to

• go through the code, importing ugettext or ugettext_lazy as _,
• then wrapping all the strings that might be translated with _("text") for python, and
• <title>{% trans "This is the title." %}</title> or <title>{% trans myvar %}</title> in templates
• then running a utility that scoops up all these strings into a .po message file
• then passing this to translators to populate with different language versions.

Django will then magically display the web interface in the right language on the fly.

Relates to issue #513

[Ed McDonagh]

Disappointed to find that you can’t use f-strings where translations are required! Will have to use the format() approach instead.

[Ed McDonagh]

Added locale folder and defined it. Added translatable string to home page template and export status (Python). Created .po file for German. Refs #512

→ <<cset e1ad6f15c60a>>

[Ed McDonagh]

Adding more strings to be translated, added more attempts at German translations. Added binary .mo file to gitignore. Refs #512

→ <<cset 2df29ffda952>>

[Ed McDonagh]

Added steps to installation/upgrade docs to generate translation binary .mo files. Refs #512

→ <<cset 515ebab771cb>>

[Ed McDonagh]

Removed specific languages from settings, minor interface edit. Refs #512

→ <<cset c922b00de054>>

[Ed McDonagh]

Adding initial German translation of docs. Refs #512 [skip ci] docs only

→ <<cset f9207119d2f3>>

[Ed McDonagh]

Issue with pip imports in German RTD project build - seems to be using this requirements file so updating. Refs #512 [skip ci] docs only

→ <<cset c2e94c3a462b>>

[Ed McDonagh]

Set both rtd yml file and config on the site to use the rtdrequirements.txt file, now can remove docs/requirements.txt. Refs #512 [skip ci] docs only

→ <<cset 05cb58e8c254>>

[Ed McDonagh]

Added a comment to the German docs to indicate they are far from complete! Refs #512 [skip ci] docs only

→ <<cset 21c3ad324fec>>

[Ed McDonagh]

Can't insert a new paragraph it seems, so replaced existing and added replaced text to previous. Refs #512 [skip ci] docs only

→ <<cset 247afb81fb02>>

[Ed McDonagh]

Adding PowerShell prompt regex. Refs #512 [skip ci] docs only

→ <<cset c001ea9ea09f>>

[Ed McDonagh]

Initial translate howto, plus English translation file to use as base for others if gettext not available. Refs #512 [skip ci] docs only

→ <<cset 7d3690fff598>>

[Ed McDonagh]

Adding gettext to docker container. Refs #512 [skip ci] docs only

→ <<cset f5c9896748cb>>

[Ed McDonagh]

Missed code-block. Also not respecting new regex for PS in German version - wiped to see if it starts working. Refs #512 [skip ci] docs only

→ <<cset 93d288a8179d>>

[Ed McDonagh]

Merged in issue512translation (pull request #393)

Fixes #512, #513

→ <<cset 2c03954d2268>>

[Ed McDonagh]

Adding ref #512, #513 to changes. [skip ci] docs only

→ <<cset 0b5709103e40>>

[Ed McDonagh]

django-admin command failed when testing docker email, manage.py worked. Refs #512

→ <<cset 4cfc9bd1812a>>

[Ed McDonagh]

Removing import made redundant in September 2020! Refs #512

→ <<cset 2145b7d2f1df>>