allow to run the plugin with no dem
added feature to enable transparent sides
	modified:   qgis2threejs.py
	modified:   qgis2threejsdialog.py
	modified:   qgis2threejsdialog.ui
	modified:   qgis2threejsmain.py
	modified:   template.html
	new file:   template_no_sides.html
	modified:   ui_qgis2threejsdialog.py
Merge branch 'olivierdalang-no_DEM'
Merge branch 'jkall-transparent_sides' and update ui_qgis2threejsdialog.py

Conflicts:
	qgis2threejsdialog.ui
move template html files into html_templates directory
fix version

0.61 is larger than 0.7
put constants into an associative array to make edit easy.
build sides only in simple resampling mode.
add a vertical spacer in DEM tab
set DEM size to 2 * 2 if no dem is selected.
that demlayerid is None means no dem layer selected.
write options into placeholder ${options}