[duneproject] fix section name in generation of config.h.cmake

When creating a project and generating the config.h.cmake file, duneproject
surrounds the inserted text with {begin,end} $NAME. $NAME is set to $PROJECT
without a leading "dune[-_]" and $PROJECT is the module name specified by the
user (e.g. $PROJECT==dune-grid, $NAME==grid).
When DuneMacro.cmake generates the config.h.cmake for the created project in
the build-directory, it searches the config.h.cmake file in the source
directory of the project for {begin,end} $ProjectName which is set to
DUNE_MOD_NAME, which is the module name specified in the corresponding
dune.module file (e.g. dune-grid).
This leads to DuneMacro not finding and therefore ignoring the block in the
source config.h.cmake of the new project.

bin/duneproject

@@ -539,7 +539,7 @@ echo "    Description and URL are missing right now."
 
 echo "- $PROJECT/config.h.cmake"
 cat> "$PROJECT/config.h.cmake" <<EOF
-/* begin $NAME
+/* begin $PROJECT
    put the definitions for config.h specific to
    your project here. Everything above will be
    overwritten
@@ -581,7 +581,7 @@ cat> "$PROJECT/config.h.cmake" <<EOF
 /* Define to the revision of $PROJECT */
 #define ${UNAME}_VERSION_REVISION @${UNAME}_VERSION_REVISION@
 
-/* end $NAME
+/* end $PROJECT
    Everything below here will be overwritten
 */
 EOF