test-revert: add methodical revert with explicit file path We now also test reverting file to the working directory parent content. However this differs from the previously introduced test by using the explicit path of each "case file" when calling revert. This should result in the same result regarding file content and backup creation, but the output of the `hg revert` call should differ.

test-revert: add methodical revert to "base" We now also test reverting s file to the content of another revision. This is still done using the `--all` flag.

test-revert: add methodical revert to parent for working directory Now that we can automatically generate states, we need to actually run revert on them and check the result. While running such tests we are checking multiple elements. The output of the `hg revert` command, the resulting content of file, and the creation of backup file. The first practical test is using the simple case `hg revert --all`, reverting all files to working directory parent content.

test-revert: display the list of all generated cases This will help to track all existing cases. (still very simple now)

test-revert: also create a text version of the snapshot The text version is just a list of existing files with their content. We use a small custom script for that. This is going to be very useful for comparing revert results with revert target content.

hg-test-mode: make exit code highlight work again

test-revert: prepare methodical testing of revert cases We introduce a script to generate revert cases and use it to prepare a test repo. See the inline documentation for details.

test-revert: drop useless comments There are multiple comments explaining the expected output of commands. This is an old relic of the pre-unified test era. We remove them for uselessness.

run-tests: don't double lines on build failure output

test-run-tests: filter pwd alias for Windows