sorting and caching

[marqh]

code lists should be sorted when they are displayed by the editing interface

for the initial cut, the ID should be sorted lexicographically

the sorting should be clearly separated to enable sorting extensions in the future

[sgtp]

Sorting should be introduced also in the latex docs. It needs a bit of refactoring as different methods are used in different parts of the code.

[sgtp]

Note that meta-information on properties is lost (e.g.: whether they are conceptual or code related properties). Do we really need this ?