Allow inserting a blank line also after a nested environment.
Add missing member initializations
Native support for \smash[t] and \smash[b]

This is a follow-up of bug #8967. The implementation is self-explaining, the
only part which needs a comment is lyx2lyx: Since a 100% correct solution is
not possible, it has been decided not to switch amsmath off in the forward
conversion if no other ams command than \smash[t] and \smash[b] is used, but
to consider it a bug that older versions do not load amsmath automatically for
these commands. In the backward direction it is easy to keep the document
compilable, so just do that.
Native support for \notag

This is mainly needed to reduce the amount of ERT if you convert AMS example
documents with tex2lyx. No GUI support is needed, since \notag is equivalent
to \nonumber.
Fix indentation of paragraphs after an environment.

When deciding whether a paragraph should be indented or not, LyX
only takes into account default layouts. This is wrong, because
an environment could be nested into another one and thus a following
paragraph would not be "default". With this patch all paragraphs
after an environment are correctly indented, independently of
whether their layouts are "default" or not.
The latex output (which was modeled following the previous wrong
assumption) is also correspondingly adapted.
Make TextMetrics::editXY more robust

This fixes a crash in examples/fa/splash.lyx when selecting text
representing menu entries. This happens because menu names are in LTR
English, while the inset itself is in RTL.

The problem is that the current code relies on the fact that
 1. getColumnNearX and checkInsetHit share the same idea about cursor
    position.
 2. pos and pos + 1 are in general consecutive on screen.

It seems that 1. is wrong here (for reasons I did not try to
understand); the second assumption is definitely false with
bi-directional text. This makes editXY very fragile.

The new code should be more robust in this respect. The logic is:
 * if checkInsetHit finds an inset, use its position,
 * otherwise, ask getColumnNearX for the cursor position.

Fixes: #9142
Avoid an assertion.

Do not assert if an inset separator is the only item of a List
environment. Although it is a weird thing to do, both GUI and
latex output can deal with it.
Fix reversion of box insets.
Fix an off-by-one error in the reversion of beamer documents.
Avoid processing multiple times the same paragraph when converting latex arguments.
Do not corrupt documents without newline at EOF

trim_eol() assumes that a line always ends either with \n, \r, or \r\n.
This assumption is always valid except for the last line of a document, since it
may miss the trailing newline. LyX does not create such documents, bu they may
result from automatic creation tools, and LyX can read them, so lyx2lyx should
be able to read them as well.
Add some SVG versions of self-made icons found here on my box
Add layout tag that determines if/when a paragraph can be indented.

Fixes: #7327, #7458, #8670
Fix the fix

MAC-style (pre-OS X) line ends were not recognized anymore
Execute lyx2lyx unit test when running tests

Actually lyx2lyx has a tiny unit test. Add it to the autotools test machinery
and fix it: Since nobody knew about it the test was of course broken.
Make layout test compile
Include lyx2lyx test in tarball
Update layouts with separators to format 50
Add missing bits of layout file format update

This is needed so that the new format number is actually used. Since the
conversion is a noop I did not update the layout files (more updates will
come).
Cleanup seminar.layout after the upgrade to format 50.