Store and load all the repositories from/to disk.
A unique directory for each kdevelop instance is used, so we don't get crashes from that.

What we store to disk now:
- Identifiers
- Macros
- 99% of environment management information(macro sets, string sets, etc.)
- Qualified identifiers
- Strings
- The complete type-system
- Comments
- C++ template instantiation information

The only missing part is the actual declarations/contexts, and the top-level environment management information.