doc/Makefile: Use SUFFIXES rather than GNU-specific %-style rules.
configure: Fixed some automake warnings.
sysdb: Use a string buffer and simple (stupid) ';' EO-query checks.

Use a different prompt (similar to psql) when inside a query.
.gitignore: Ignore ar-lib.
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.
Moved connection-private.h from src/include/frontend/ to src/frontend/.

This header is not meant to be used anyway else, so don't lead people into
temptation.
.gitignore: Ignore sysdb / sysdbd only as src/sysdb / src/sysdbd.