r.sim.terrain: bugfix, refactoring, docs (#578)

src/raster/r.sim.terrain/r.sim.terrain.html

@@ -93,19 +93,18 @@ <h2>EXAMPLES</h2>
 <h2>ERROR MESSAGES</h2>
 
 If the module fails with
-
 <div class="code"><pre>
-ERROR: nwalk (7000001) &gt; maxw (7000000)!
+ERROR: Unable to insert dataset of type raster in the temporal database. The mapset of the dataset does not match the current mapset.
 </pre></div>
-
-then a lower <b>nwalkers</b> parameter value has to be selected.
+check that the input  <b>elevation</b> map is in the current mapset.
+The input <b>elevation</b> map must be in the current mapset
+so that it can be registered in the temporal database.
 
 <h2>REFERENCES</h2>
 
 <ul>
 <li>
-Harmon, B., Mitasova, H., Petrasova, A., Petras, V., 2019.
-<a href="https://github.com/baharmon/landscape_evolution/raw/master/tex/landscape_evolution.pdf">r.sim.terrain: a dynamic landscape evolution model</a>.
+Harmon, B. A., Mitasova, H., Petrasova, A., and Petras, V.: r.sim.terrain 1.0: a landscape evolution model with dynamic hydrology, Geosci. Model Dev., 12, 2837–2854, <a href=https://doi.org/10.5194/gmd-12-2837-2019>https://doi.org/10.5194/gmd-12-2837-2019</a>, 2019.
 </li>
 <li>
 Mitasova H., Barton M., Ullah I., Hofierka J., Harmon R.S., 2013.
@@ -115,6 +114,7 @@ <h2>REFERENCES</h2>
 </li>
 </ul>
 
+
 <h2>SEE ALSO</h2>
 
 <em>