Integrate the new reporter specs into Catch2

This means that the CLI interface now uses the new key-value oriented
reporter spec, the common reporter base creates the colour implementation
based on the reporter-specific configuration, and it also stores the
custom configuration options for each reporter instance.

Closes #339 as it allows per-reporter forcing of ansi colour codes.

tools/scripts/approvalTests.py

@@ -220,7 +220,7 @@ common_args = ["~[!nonportable]~[!benchmark]~[approvals] *", "-s", "-w", "NoAsse
 filenames = ['{}.sw.multi'.format(reporter) for reporter in reporters]
 reporter_args = []
 for reporter, filename in zip(reporters, filenames):
-    reporter_args += ['-r', '{}::{}'.format(reporter, get_rawResultsPath(filename))]
+    reporter_args += ['-r', '{}::out={}'.format(reporter, get_rawResultsPath(filename))]
 
 run_test("default.sw.multi", common_args + reporter_args)
 check_outputs("default.sw.multi")