#100 Enable private caches

[Erik Hänel]

It would be quite helpful, if NumeRe's procedures would be capable of creating and using private caches. Should not be too difficiult, as the program's logic should be nearly the same.

Analysis:
Because of the the other commands str and var being an abbreviation, one could for example choose the term tbl as an abbreviation for table as the command for creating private caches. Except of this, the changes include the enabling of using special characters in the caches names (i.e. _~), the management of new local variables including their deletion and probably the enabling of the private caches in the debugger environment, however, this may also be done outside of this ticket.
For simplification one can also change the behavior of the local variables in complete, e.g. create management classes for them, so that maintenance on them is more easy. And it is also imperative to apply some rework on the procedure logics.

Implementation:
The change was implemented as proposed by the analysis. The command was renamed to tab as this is more intuitive. The management of the local procedure variables was also changed to a central variable factory.
In addition, the code analyzer was also modified, so that it can detect, whether a local cache is actually used.
Implementation tests were passed successfully.

Documentation:
The command tab was added to the language files, to the syntax elements, to the documentation article about procedure commands and to the protected commands regarding plugins.

Tests:
No deviations detected. Functionality was implemented successfully.