[LyX/master] Don't allow inserting two consecutive separators.

[Enrico Forestieri]

commit 10d5897327bfe6d7f2768e1f7fa4d7beb8f556e4
Author: Enrico Forestieri <for...@lyx.org>
Date:   Sun May 18 18:02:25 2014 +0200

    Don't allow inserting two consecutive separators.

diff --git a/src/Text3.cpp b/src/Text3.cpp
index b12f094..2c2cba4 100644
--- a/src/Text3.cpp
+++ b/src/Text3.cpp
@@ -1073,6 +1073,7 @@ void Text::dispatch(Cursor & cur, FuncRequest & cmd)
                Paragraph const & par = pars_[pit];
                Paragraph const & prevpar = pit > 0 ? pars_[pit - 1] : par;
                if (pit > 0 && cur.pos() == par.beginOfBody()
+                   && !par.isEnvSeparator(cur.pos())
                    && ((prevpar.getDepth() > par.getDepth()
                         && !par.layout().isEnvironment())
                        || (prevpar.layout() != par.layout()