purge old doc/plugins directory
purge olde PluginInstallerDialog context help

there will be a new QgsPluginManager help file
delete unused resource files

if I understand jef correctly, these files are all not used anymore (plz correct
me if I'm wrong).
The build and scripts incorporate the en_US resource files in the corresponding
i18n/qgis_**.ts files (by creating cpp from it).
Fix #4189
Partial fix #7708
Fix QgsVectorLayer::EditType API doc
fix #8396
translation update: da by Jacob
Fix possible crash on exit
Update 'Add WMS Layer...' to 'Add WMTS/WMTS Layer...' (followup d1de07a2)
and finish german translation

--
perl -0777 -i.bak -pe 's#<source>Add WMS Layer...(</source>\s+<translation)>#<source>Add WMS/WMTS Layer...$1 type="unfinished">#' i18n/qgis_*.ts
perl -i.bak -pe 's#<source>Add WMS Layer...</source>#<source>Add WMS/WMTS Layer...</source>#' i18n/qgis_*.ts
[pyqgis-console][fix #8392] automatically removes the redundant char when autoclosing brackets option is enabled
[dbmanager] avoid double extension when exports to file a table
[ftools][fix #8390] fix typo
change window title
Russian translation update.
Fix untranslatable string in QgsRasterDataProvider
Russian translation update.
Add plural form in QgsMessageBar
Correct window title in the export error messagebox.
german translation update