func-test: create a separate target for slow functional tests

With this patch "make check" will only run unit tests (still contains a
number of not fast-enough programs, but they are still faster
than func-test).

Signed-off-by: Balazs Scheidler <bazsi@balabit.hu>
rewrite: move to a subdirectory of lib/

This patch moves the rewrite functionality under a new subdirectory
to make the source code easier to navigate.

Signed-off-by: Balazs Scheidler <bazsi@balabit.hu>
parser: move to a subdirectory of lib

This patch moves the rewrite functionality under a new subdirectory
to make the source code easier to navigate.

Signed-off-by: Balazs Scheidler <bazsi@balabit.hu>
filter: move to a subdirectory of lib

This patch moves the filter functionality under a new subdirectory
to make the source code easier to navigate.

Signed-off-by: Balazs Scheidler <bazsi@balabit.hu>