Bug 28898: Context for translation: term (word) vs. term (semester)

Bug 28898: Context for translation: term (word) vs. term (semester)

This patch add context to the term Term in the context of course reserves.

To test:
0- Apply patch
Set up course reserves
1- Enable UseCourseReserves
2- Create at least one authorized value for DEPARTMENT
3- Create at least one authorized value for TERM
4- Create a course
5- Add at least one item to the course

Check the terms:
6- Go to the OPAC
7- Go to Course reserves
** 8- In the list of courses, check the Term column heading
9- Go to the staff interface
10- Go to Course reserves
** 11- In the list of courses, check the Term column heading
12- Click on the course name
** 13- Check the Term line in the course description

Add a new language (fr-CA in the example, change for whatever language code you want)
14- In a terminal, run
gulp po:create --lang fr-CA
15- Then, run
gulp po:update --lang fr-CA
16- In system preferences, enable the new language in language and OpacLanguages
17- Switch the language in staff interface and OPAC

Change the translations
18- In your favourite text editor, open fr-CA-messages.po
19- Find the string 'msgctxt Semester'
20- Enter a word in msgstr
21- Save the file
22- In a terminal, go to misc/translator
23- Run
./translate install fr-CA

Check the translations
24- Redo the steps to check the terms (6-16) and make sure the terms in steps 8, 11, and 13 are changed for the word you put in step 20.
25- Optionally, check the following pages to make sure the terms are not the word you put in step 20 (these pages shouldn't have been changed)
- opac-tags (your account > your tags)
- opac-authorities (search for an authority in Authority search)
- review (tags in staff interface)

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Julian Maurice <julian.maurice@biblibre.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>