Hacking copy of main branch into index.json

[AnHeuermann]

Changes

• Adding copy of main/master/trunk entry into index.json
• Don't skip duplicate entries for the main/master/trunk prerelease

[AnHeuermann]

With this version of index.json I could run installLibraries.mos, but I had to remove some libs from ~/.openmodelica/libraries/ to resolve missing 4.2.0-master of the MSL:

[~/.openmodelica/libraries/index.json:0:0-0:0:readonly] Error: The package index did not contain an entry for package Modelica of version 4.2.0-master. There are other versions that claim to be compatible: master.

Not sure if we want to add an entry for that one to our rawdata.json, since the MSL changed the naming sceme.

[AnHeuermann]

Also this conflict isn't looking good:

[~/.openmodelica/libraries/TILMedia 1.8.0-ClaRa/package.mo:0:0-0:0:readonly] Notification: Package installed successfully (SHA 0fd90ee65236266b94c4c6193d18dbbe3f41af38.zip).
[~/.openmodelica/libraries/ClaRa 1.8.0/package.mo:0:0-0:0:readonly] Notification: Package installed successfully (SHA 7240de943923575973f5a0007cbffeecf0939f28.zip).
Warning: Conflicting versions for loading package TILMedia: 1.9.0-ClaRa is to be installed, but another package requires version 1.8.0-ClaRa which is not provided by this version.

I hope this doesn't affect the nightly tests.