Avoid using HTML tags in translation strings (includes/admin/topics.php)

[ramiy]

In this ticket, we simplify the translation strings, like we did in ​wordpress code. Removing the HTML tags from translation strings to make the translation process faster and easier.

See the attached patch.

---

Old strings:

• Topic updated. <a href="%s">View topic</a>
• Topic created. <a href="%s">View topic</a>
• Topic submitted. <a target="_blank" href="%s">Preview topic</a>
• Topic draft updated. <a target="_blank" href="%s">Preview topic</a>

New strings:

• Topic updated.
• Topic created.
• Topic submitted.
• Topic draft updated.
• View topic
• Preview topic

[ramiy]

Related: #2881

[ramiy]

Related: #2911

[ramiy]

Related: #2912

[thebrandonallen]

Updates patch to apply cleanly on latest trunk. Also, removes more HTML and adds one new string:

Topic scheduled for: %s.

This brings us in line with the way WP handles scheduled posts in the admin.

[thebrandonallen]

Remove new string from patch, as this is handled in #2881.

[netweb]

In 6043:

i18n: Avoid using HTML tags in translation strings (includes/admin/forums.php)

Props ramiy, thebrandonallen
Fixes #2910