Check validity of constraints' lvalues during PolicyCheckPartial().

The same check existed in the parser so I removed it. Validity of constraints
is now checked in ConstraintCheckSyntax(), copied from ConstraintGetSyntax()
which now expects syntax is already checked.

Also fixed a segfault, so changed the relevant acceptance test to not expect
crash, but just failure.
Merge pull request #401 from cduclos/master

Fixing a unit test failure.
Allow empty lists at the language level.

Translates empty lists { } => { "cf_null" } in the parser.
Arguably a hack, but much simpler than removing cf_null itself.
RVAL_TYPE_ASSOC is unused, kill it.
Merge pull request #403 from jimis/assoc-kill

RVAL_TYPE_ASSOC is unused, kill it.
Merge pull request #402 from sigurdteigen/feature/language-empty-lists

Allow empty lists at the language level.
add namespaced acceptance tests as per https://cfengine.com/dev/issues/1400
Add another acceptance test for cf_null inputs
Fix segfault in template rendering

Resulting from temporary bundle having no set namespace.
Factor out files_editline.h, constify
Avoid ad-hoc bundles in MakeTemporaryBundleFromTemplate, leak
Ignore Automake test suite files
Move IsReadReady to the proper place
Fix segfault with duplicate handles. Issue #2267
Merge pull request #404 from tzz/tests/array-across-namespaces

add namespaced acceptance tests (try#2)
Merge pull request #405 from baptr/issue-2267

Fix segfault with duplicate handles. Issue #2267
Merge pull request #397 from jimis/bug2230

Check validity of constraints' lvalues during PolicyCheckPartial().
Fix for acceptance tests.

It turns out that using printf and stat is not such a good idea, since
their behavior change from platform to platform.
This commit changes the mode test to a little perl script.