Correct detection of journal end position.

MR !316

This fixes an issue where the journal file could grow over the set
limit if:
1. Last entry on previous rollover did not fill the file fully
2. The information about the difference between the last entry and the
file size is lost

In such case, the end of file is detected later, leading to
increase of the file size by the size of the first evicted entries.

lookup table: checking parameters
serial compare: legal corner cases proper testing
                (Maybe they should be ommited, because it would
                also be legal if the comparisons had opposite
                results. But at least we will know if we change
                something.)

TODO: Handle the undefined corner cases of serial difference.
TODO: NULL arguments to lookup table?

refs #309

See merge request !313

DNSSEC: Single-Type Signing

See merge request !312

refs #309

Journal fsize

Fixed journal file size / limit arithmetics when the file size was larger than the imposed limits.
Added unit tests for overfill / fillup and file size checks.

See merge request !311

Removed CRC check from journal

See commit fed2e5c2.

See merge request !310

knotc improvements

Improved `knotc` commands + unified and improved help, man and documentation.

- `reload` and `zonestatus` now take arguments and can be called for particular zones
- fixed logging of incoming command (was printing only the last argument)
- fixed use of RCU in remote command processing.
- updated help (`knotc -h`), man page and doxygen documentation
- warning when no arguments are supplied to `refresh -f` and `signzone` (they require at least one argument)
- warning when arguments are passed to `stop` and `checkconf` (they take no arguments)

Fixes #308

See merge request !309

CRC in the journal is replaced by a placeholder to maintain the
journal format.
Removed the zlib dependency.

- libknot-int exports all symbols
- pkg-config is updated to make the change transparent