Improvements:
* Memoise git config lookups (big speedup!)
+ * Switch to new production git repositories for reading.
+ (this can no longer divert to alioth).
Documentation:
* dgit(1): Remove some obsolete caveats from BUGS.
Access machinery:
* Provide for different access mechanisms when pushing.
* Provide for configurable git url suffix.
+ * Provide for checking git presence via http[s].
* Do some quoting on debug output (needed if the server might not
be trustworthy and might send us bad stuff).