- Built generic interface for alternative script sources.
  - Implemented dict script location.
  NOTE: ManageSieve will not work with this yet, nor will sieve_before/sieve_after.

- Added sieve_global_extensions setting.

- Administrators now get properly notified about uncompiled global scripts and the inability of the sieve plugin to store global binaries.
- Improved binary load/save error handling and fixed a few smal bugs.
- Simplified ManageSieve error handling.

Added registry for extension capabilities like the available notify methods and adjusted the enotify extension accordingly.

Made lda plugin properly refer to the main script as 'main script' and not the basename of the sieve file (which is of no interest to the user for the main script).

Made error reporting cleaner by avoiding the scriptname of the main script and indicating that the printed numbers are in fact source code lines.