Added a page to explain the heightmap template editor.

Heightmap-template-editor.md

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+The templates indicate what must happen to the heightmap.  The template has instructions that take place
+one after another, all in a list.  Each instruction can do various things:
+
+Those things are:
+* Add a hill (raises surrounding land)
+* Add a pit (lowers surrounding land)
+* Add a range (a thin raised section)
+* Add a trough (a thin lowered section)
+* Add a strait (a vertical or horizontal lowered section)
+* Add or subtract from all heights
+* Multiply all heights
+* Smooth all heights
+
+Once you have given all the instructions, you can then run the template (process all instructions in sequence).
+There are also options to save or load templates.
+
+When running a template, the map is cleared first.
+
+For each instruction, it can have the following values:
+n - the number of times it must occur
+h - the height range, from 1-100 where 1 is deep ocean, and 100 is maximum height.  20 is land at sea level.
+x and y - percentage values (from 1-100) indicating where the change must take place - these are usually ranges.
+  x is the horizontal axis, from 1 at the left, to 100 on the right.
+  y is the vertical axis, from 1 at the top, to 100 at the bottom.
+
+If you go to Custom, it will show an instruction like this:
+Hill    n:1    h:90-100   x:65-75   y:47-53.
+
+This says to add 1 hill, of a height between 90-100, somwhere in the center-right of the map.  y says more-or-less center 47% to 53%, and x says 65% to 75%.
+
+
+To test it, change the single Hill entry to:
+Hill    n:1    h:20   x:50-50   y:50-50
+
+If you click Run template, it will show a map with just a few cells of land right in the center of the map.
+
+![Heightmap showing a single hill of height 20](https://evolvedexperiment.github.io/FMGImages/images/template1.png)
+
+I suggest you enable "Render ocean cells" to see the effect it has on the ocean depths.
+
+Now change n:1 to n:2
+
+You will see massive change - this is because the land has been raised by 40 height values.
+
+![Heightmap showing two hills of height 20 at the same place](https://evolvedexperiment.github.io/FMGImages/images/template2.png)
+
+Now Pit is the opposite of Hill - it will create a "hole".
+
+To test it, add a Pit so your instructions look like this:
+Hill    n:2    h:20   x:50-50   y:50-50
+Pit     n:1    h:20   x:50-50   y:50-50
+
+Run it and you will see a hole - the exact look will vary a bit.
+
+![Heightmap showing two hills and pit at the same place](https://evolvedexperiment.github.io/FMGImages/images/template3.png)
+
+Now add a range and disable the Hill and Pit entries.
+
+You will see it makes a short raised area.
+Range   n:1    h:40-50   x:15-85   y:20-80
+
+![Heightmap showing a single range](https://evolvedexperiment.github.io/FMGImages/images/template4.png)
+
+If you change the Range and enable the Hill and Pit, you will see that it combines:
+Hill    n:2    h:20   x:50-50   y:50-50
+Pit     n:1    h:20   x:50-50   y:50-50
+Range   n:1    h:40-50   x:50-60   y:50-50
+
+![Heightmap showing two hills, a pit, and a range.](https://evolvedexperiment.github.io/FMGImages/images/template5.png)
+
+Trough works exactly like Range, except that it lowers height.
+
+Delete all the instructions and click on the +
+The + instruction adds height - it can have a negative value to lower height.
+
+Change the V to 20 so your whole line looks like this:
+Add     V:20    to all cells
+
+Run it and it will change to whole map to land at sea-level - remember that 20 is just above sea-level.
+Add a Strait - it only has 2 values, width and direction:
+w - width 
+d - vertical or horizontal
+
+Run it and you will see land divided by a river somewhere - note that you cannot control the location.
+
+![Heightmap showing a strait](https://evolvedexperiment.github.io/FMGImages/images/template6.png)
+
+Multiply works similar to add, except you have slightly better control to adjust small things, so multiplying by 1.1 
+will make raise land slightly - smaller changes to low values, and larger changes to high values.  You can multiply 
+by decimals as well, so multiply by 0.8 will lower everything a bit.
+
+The last one is smooth - this should probably be at the end - all cell heights are averaged by their neighbours heights.
+This means land next to a pit will lower, and land next to a hill will rise.  Smooth removes any spiky bits near land
+and generally makes performance better on the FMG.
+
+![Heightmap showing a strait between two hilly areas.](https://evolvedexperiment.github.io/FMGImages/images/template7.png)