Log Message:
Update to 1.4.2. From the changelog:

documentation:

* Replace auto-generated list of the supported MIME types with an
  auto-generated table showing the extensions that are mapped to each MIME type
  by default.  Partly addresses #569, reported by catkin.

indexers:

* omindex: Add support for indexing markdown files (extension .md or .markdown,
  mime-type text/markdown, using "markdown" to convert to HTML).

testsuite:

* Add support for "make installcheck" to run tests against installed \ 
version.

build system:

* configure: Fail with clear error with xapian-core < 1.4.0.

portability:

* Fix GCC -Wimplicit-fallthrough warning.

* Add missing <ctime> for time_t.

* Avoid snprintf_for formatting fixed-width integers - it results in warnings
  about possible output truncation with GCC7 (which aren't actually possible
  due to limited input range) and it's a bit heavyweight for this job anyway.