HashTable is semi-mutable

[Martin Sjölund]

The HashTable contains some fields that are mutable and some that are not. If it should be an immutable structure, it needs to use vectors instead of arrays.

But it should be mutable. It's used under the assumption that it is anyway.

Solution: Make all the scalar fields in a HashTable into arrays of size 1, or encapsulate it into type HashTable = HashTableImpl[:].

[Martin Sjölund]

Problem: If you make this mutable as it should be, the FunctionTree structure is no longer always generated.

[Martin Sjölund]

Created branch ​https://openmodelica.org:8443/cb/proj/sources/sccFileLog.do?proj_id=1&filename=branches/sjoelund-functiontree&isDir=true

The initial step is to move FUNCTION from Element to Function uniontype. Then we need to move FunctionTree from DAE.DAElist to Env.Cache. After that, we can make the FunctionTree mutable.

[Martin Sjölund]

The branch now uses a non-mutable hashtable which solves this issue (but the branch is not 100% testsuite compatible yet). Note that the issue still remains (updating a value in the hashtable is mutable; adding a new value is not).

[Martin Sjölund]

I'm too tired to fix this :(