De-duplication of icons from the python icon generator script

[dietmarw]

The new icon generator has one major flaw and that is it is a proper space hog. Lot's of Modelica classes have the same icon (e.g., Modelica.Icons.Information) still the generator will save a separate copy for each of them. There is a rather simple solution that is based on the same de-duplication principle that Git VCS uses for the internal data storage. All files are saved not under their name but using the hash of their content as file name and an index to connect the original file name with the correct stored file name.

Something similar can be done for the icon file names and we should not even need an index file. Here is the principle as you can implement it in Python. Not really sure how to hook this into the GenDocumentation.mos really:

>>> import hashlib
>>> filename=hashlib.sha1("Modelica.Icons.Information").hexdigest()+'.svg'
>>> print  filename
43a93cda6b266a395248252cb4b69d1e9a0837af.svg

This means all classes using the same class as icon can simply point to same svg file. No need to store another version.

_{I could not really find a correct component to assign this ticket to. It should probably belong to "IconGenerator" or "Documentation Generator"}

[sjoelund.se]

You actually do need some way to connect the classname to the hash because the mos-script and python-script are different. Also, I need some way of removing <desc>Modelica.XXX.YYY</desc> from the svg because otherwise they are all different.

[sjoelund.se]

Fixed in r17968

[dietmarw]

Two thinks I'm still missing in order to make this suitable for usage of a release generator:

1. If readSymlinks = true then the symlinks should not be generated. (btw, unfortunate choice of name since it could be interpreted as "readABLESymlinks")
2. There should be a "release" switch that does not generate all the space hungry json files. The whole de-duplication does not make sense if we keep the even larger jsons for ALL classes.

[dietmarw]

I am aware that this can be easily done in the script (see also ​m:r7114) but it would be more elegant if those file where not created in the first place depending on a "switch".

[sjoelund.se]

"Fixed" in r17993, basically as above.