Fix for writing out point files, when only one point is used.
The code was testing for > 1 points to be present, before writing out point files.
Bug #22753 (https://gna.org/bugs/index.php?22753): dx.map does not work when only 1 point is used.
Authored by: tlinnet 2014-10-05
Parent: [r26149]
Child: [r26151]
