Allow bool literals in CompiledSubdomain expression.
Get as_backend_type working for LinearOperator.
Merge branch 'blechta/fix-issue-342'
Fixes Issue #335 (fix from Steven Vandekerckhove)
Merge branch 'stevenvdk/fix-issue-335' into next
Add unit test for bool CompiledSubDomain expressions.
Merge branch 'blechta/fix-issue-301' into next
Merge branch 'blechta/fix-issue-336' into next