Remove autotools files

In preparation for package w/ web installer installations all autotools files must be removed
because the installation method using the latter will no longer be supported.

refs #7505
tests: remove extcmd_test

extcmd_test is no longer used anywhere because I removed all command pipe tests.
Remove files related to API doc

I remove these files because the script for creating the API was removed too.
But we'll re-add them sometime I guess.
Clean .gitignore file

Note to all developers: You must not add your local crap here.
Use .git/info/exclude.
Do not spread .gitattributes over multiple files
Remove config/*.in files
Remove example config files memberships, permissions and restrictions
Add standard authentication.ini
Merge branch 'master' into feature/remove-autotools-files-7505
Remove sample apache configuration

Our CLI will generate webserver configuration.
Merge branch 'master' into feature/remove-autotools-files-7505
Merge branch 'feature/remove-autotools-files-7505'

resolves #7505
Merge branch 'master' into feature/localization-form-6073
Use 'Preferences' instead of 'General Settings'

refs #6073