ja.po from Koji
ctests for broken URLs in URL insets of LyX docs

These tests check for broken URLs in the URL insets of
the manuals, examples, and templates.

The tests are disabled by default because the Perl interpreter
is needed.

Later on they can be activated with a flag, as follows:

  cmake ... -DLYX_ENABLE_URLTESTS=ON

but for now the connection from the TOP-CMakeLists.txt is left out.

Missing part:
        1.) Declaring an setting the option
                LYX_OPTION(ENABLE_URLTESTS  "Enable for URL tests" OFF ALL)
        2.) make the connection
                if(LYX_ENABLE_URLTESTS)
                        add_subdirectory(development/checkurls "${TOP_BINARY_DIR}/checkurls")
                endif()
Update source list
Replaced some invalid urls
Replaced some more invalid urls
Cmake build tests: href entries checked

Our lyx-files are referencing urls also with
a href inset. We check now also these.

search_url.pl: Added check for href
*.lyx: Corrected href
Remerge and update of ja.po (from Koji)
Catch uncodable character problem
Fix shortcut clash (#8813)
Restore translations after rev c25f339f3f8
de.po: Fix shortcut clash
sk.po: Some shortcuts and capitalisation
Replace the remaining bad urls with accsessible ones

Now all urls we use in our provided lyx-files
(doc, examples, templates)
use urls which really exist.

(If a url was meant merely as an example,
it was not touched, but added to file 'knownInvalidURLS'.)
Comments only.
Fix obvious oversight.
Load AMS packages before newtxmath (#8824)
Allow master view/update when current buffer is the master
Add outline-{up,down} to alt-{up,down} binding

Now when the cursor is in e.g. a Section layout, alt-<down>
will dispatch 'outline-down'. Before, it would dispatch a
'paragraph-down', which I think makes less sense.