Dragging a standing signal over the track takes it to the other side;
the side used to come from where the signal stood, so it never crossed.
The selected signal gets "To the other side" and "Turn around": the
first mirrors it over the axis facing the same trains, the second turns
it to the trains of the other direction and moves its event to the
other event list of the path. Either one swaps a head leaning to the
track for its counterpart, and an include keeps the template its
directive names, so undo brings the old file back too.
- Terrain work mode shows a browser of the textures folder in place of the
node bank; textures/materials can be dragged onto the palette entries
(replacing the material), the material field and the water material field
- Ctrl+Z/Ctrl+Y for heightmap terrain changes: a brush stroke or an
operation is one step of the editor history
- Ground conversion reads only the files of the terrain directives
(.txtf with origin/rotate, or .btf without text), paints the chunks with
the materials of the triangles, drops only the shapes of those files
- Fix: ground grids converted out-of-range floats to int, so whole-scene
queries returned the triangles of a single cell (shifted chunks)
- Fix: terrain layers copied from textures already uploaded without their
data stayed grey
- Fix: ImGui ID conflict between terrain tool radios and section headers
- Fix: layers of terrain .txtf files named with the scenery/ prefix and
could not be saved
- Editor selftest commands for the terrain
