Fix bug 3143 by Richard Heck. Background information from Richard:

Fix bug 3143 by Richard Heck. Background information from Richard:

breakParagraph seems to be called five times: in buffer.C, by
insertStringAsLines; and in text3.C, for LFUN_BREAK_PARAGRAPH,
LFUN_BREAK_PARAGRAPH_KEEP_LAYOUT, LFUN_BREAK_PARAGRAPH_SKIP (which
itself calls LFUN_BREAK_PARAGRAPH if a paragraph will be broken), and
for LFUN_FLOAT_LIST. My sense was that the KEEP_LAYOUT version maybe
shouldn't reset the text style.  That's why I put it where I did. But I
doubt it matters very much, and I had it in breakParagraph myself at one
point.

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@17612 a592a061-630c-0410-9148-cb99ea01b6c8