Moved sysdb and sysdbd sources to src/tools/. Also, moved all purely private headers to that directory as well. Renamed some files for greater consistency.
sysdb: Use a string buffer and simple (stupid) ';' EO-query checks. Use a different prompt (similar to psql) when inside a query.
strbuf utils: Added sdb_strbuf_clear().
sysdb: Free memory allocated by readline().
sysdb: Don't warn about missing history file when loading history.
sysdb: Check for and use libedit/libreadline for command input.
sysdb: Exit, if the current user could not be determined.
sysdb: Use error utilities.
sysdb: Connect to the server and issue a STARTUP command. The current username is sent along with the STARTUP command.
sysdb: Added a initial client implementation. For now, this is basically a placeholder.