sort sects about plugins to follow the order in plugin page in the settings dialog, add missing links

Sync kate docbook with https://git.reviewboard.kde.org/r/127601/ Remove Editor Component Extensions from katepart
Sync menu items
REVIEW:127841

Group box titles use capitalized first characters.

@kde-i18n-doc: Is it ok to backport this to the 16.04 branch?

CCMAIL: codestruct@posteo.org
CCMAIL: kde-i18n-doc@kde.org

In case of conflict in i18n, keep the version of the branch "ours"
To resolve a particular conflict, "git checkout --ours path/to/file.desktop"

In case of conflict in i18n, keep the version of the branch "ours"
To resolve a particular conflict, "git checkout --ours path/to/file.desktop"

In case of conflict in i18n, keep the version of the branch "ours"
To resolve a particular conflict, "git checkout --ours path/to/file.desktop"

CCBUG: 362447

BUG: 362447

In case of conflict in i18n, keep the version of the branch "ours"
To resolve a particular conflict, "git checkout --ours path/to/file.desktop"

In case of conflict in i18n, keep the version of the branch "ours"
To resolve a particular conflict, "git checkout --ours path/to/file.desktop"

In case of conflict in i18n, keep the version of the branch "ours"
To resolve a particular conflict, "git checkout --ours path/to/file.desktop"

In case of conflict in i18n, keep the version of the branch "ours"
To resolve a particular conflict, "git checkout --ours path/to/file.desktop"

In case of conflict in i18n, keep the version of the branch "ours"
To resolve a particular conflict, "git checkout --ours path/to/file.desktop"

In case of conflict in i18n, keep the version of the branch "ours"
To resolve a particular conflict, "git checkout --ours path/to/file.desktop"

proofread + update
REVIEW:127707

With http://marc.info/?l=kde-commits&m=131428430807601&w=2 the plugin "Tree View" was renamed to "Documents"
But in the Plugin Manager settings window it is still named "File Tree" not "Documents" as in other places in the GUI.
REVIEW:127721

Thanks to Roberto Castagnola for the patch!
BUG: 361909
REVIEW: 127690

Michal Humpula authored Apr 23, 2016 and Dominik Haumann committed Apr 24, 2016

New versions of Qt silenty started to return "." instead of "" as
result of `QDir("/tmp").relativeFilePath("/tmp")`.

Adding aditional check for "." to fix it.

REVIEW: 127731

New versions of Qt silenty started to return "." instead of "" as
result of `QDir("/tmp").relativeFilePath("/tmp")`.

Adding aditional check for "." to fix it.

REVIEW: 127731

If plugin's library is missing a shared library, the factory might be
null but the load state is not reset to false. Also add another check
when using loadPlugin but without check the loading state.

REVIEW: 127685

In case of conflict in i18n, keep the version of the branch "ours"
To resolve a particular conflict, "git checkout --ours path/to/file.desktop"

This was due to several commits ending up only in the Applications
branch, to ensure things don't diverge too further.

Conflicts:
    CMakeLists.txt [versioning]