DEPM and crash regressions in branch

[Uwe Stöhr]

- create a new LyX file
- create two paragraphs
- at the end of the second paragraph press enter to create a new one
- now press either:

Arrow up -> the empty paragraph is not removed -> regression to LyX 1.6.2
or
Arrow down -> LyX crashes -> regression to LyX 1.6.2

regards Uwe