basicfuncs: actually run unit tests for various template functions

These calls were somehow factored out and thus unit tests were not actually
run. Fortunately no functions were broken in the meantime.

Signed-off-by: Balazs Scheidler <bazsi@balabit.hu>
basicfuncs: added unit test coverage for $(indent-multi-line)

Signed-off-by: Balazs Scheidler <bazsi@balabit.hu>
versioning.h: introduce syslog-ng 3.5

This patch allows the use of the '@version: 3.5' cookie in syslog-ng.conf
files.

Signed-off-by: Balazs Scheidler <bazsi@balabit.hu>
affile: rename no_expand to filename_is_a_template

Double negation as happened with this variable name is difficult to decipher,
so change no_expand to filename_is_a_template that makes the code
easier to read.

Signed-off-by: Balazs Scheidler <bazsi@balabit.hu>
affile: introduce multi-line-mode() option

This patch adds the multi-line-mode option to the file/pipe sources so
that lines can be continued by indenting subsequent lines can be used.

Use:
  file("/foo/bar" multi-line-mode(indented));

The file should have this format:

first line
  continuation line 1
  continuation line 2
second line

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