Adds Talkpage monitoring

[thomas-topway-it]

This PR is made in reference to: #67

• adds $stgNotifyOnDeleteTaskArticle and $stgNotifyOnTalkPageEditOfTaskArticle global parameters
• adds DELETED, TALK_CREATED, TALK_EDITED and TALK_DELETED statuses
• handle talk page via method getEffectiveArticle
• updates version to 3.1.0

This PR includes:

• Tests (unit/integration)
• CI build passed

[codecov]

Codecov Report

❌ Patch coverage is 10.00000% with 72 lines in your changes missing coverage. Please review.
✅ Project coverage is 12.78%. Comparing base (ec12dc9) to head (10e17ff).
⚠️ Report is 11 commits behind head on master.

Files with missing lines	Patch %	Lines
src/SemanticTasksMailer.php	12.06%	51 Missing ⚠️
src/Assignees.php	4.54%	21 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master      #68      +/-   ##
============================================
+ Coverage     11.83%   12.78%   +0.94%     
- Complexity       79       95      +16     
============================================
  Files             4        4              
  Lines           321      352      +31     
============================================
+ Hits             38       45       +7     
- Misses          283      307      +24     

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