IDEA-96893 IDEA doesn't remember window position on restart if several projects are open [nik]
[hg tests] Make hg tests not light, but heavy

Light tests are not suitable, because hg tests need to work with a real
file system and recreate project and project directory.

Therefore, extend from simply UsefulTestCase and manually set up
fixtures.
IDEA-103344 for inspection ('Remove unnecessary parentheses' incorrectly suggests to remove parentheses)