Btest

* Adding support for "parts": One can split a single test across
multiple files by adding a numerical ``<n>`` postfix to their
names, where each ``<n>`` represents a separate part of the test.
``btests`` will combine all of a test's parts in numerical order
and execute them subsequently within the same sandbox. Example in
the README. (Robin Sommer)

* When running a command, TEST_PART contains the current part
number. (Robin Sommer)

* Extending Sphinx support. (Robin Sommer)

* Adding tests for Sphinx functionality.

* Support for parts in Sphinx directives. If multiple btest
directives reference the same test name, each will turn into
a part of a single test.

* Internal change restructuring the btest Sphinx directive. We
now process it in two passes: one to save the test at parse
time, and one later to execute once everything has been
parsed.

* Adding Sphinx sandbox for testing.

* Fix for tests returning no output to render at all. (Robin Sommer)

* btest-diff now passes the name of the file under consideration on to
canonifiers. (Robin Sommer)

* When searching for tests, BTest now ignores a directories if it finds
a file ".btest-ignore" in there. (Robin Sommer)

* Fixing bug with TEST-START-NEXT naming. (Robin Sommer)

* A test-suite for btest. Using, of course, btest. "make test" will
test most of btest's features. The main missing piece is testing
the Sphinx support, we will add that next. (Robin Sommer)

* When creating directories, we know also create intermediaries.
That in particular means that "TEST-START-FILE a/b/c" now creates
a directory "a/b" automatically and puts the file in there. (Robin
Sommer)

* IgnoreDirs now also works for sub directories. (Robin Sommer)

* Documentation updates. (Robin Sommer)

* Adding "Initializer" option, which runs a command before each
test. (Robin Sommer)

* Adding "CommandPrefix" option that changes the naming of all btest
commands by replacing the "TEST-" prefix with a custom string.
(Robin Sommer)

* Default configuration file can be overriden via BTEST_CFG
environment variable. (Robin Sommer)

* s/bro-ids.org/bro.org/g (Robin Sommer)

* Bugfix for -j without number. (Robin Sommer)

* New TEST-ALTERNATIVE that activates tests only for the given
alternative. Renamed TEST-NO-ALTERNATIVE to
TEST-NOT-ALTERNATIVE, and allowing "default" for both
TEST-ALTERNATIVE and TEST-NOTALTERNATIVE to specify the case
that BTest runs without any alternative given. (Robin Sommer)

* Fix for alternative names containing white spaces. (Robin Sommer)

* Fixing links in README and removing TODOs. (Robin Sommer)