Remove obsolete apps, tests, and scripts

I propose to delete the following applications, tests, and scripts that are either obsolete or unmaintained:

apps/performance/*

apps/tests/HelloTest

apps/toys/FXSlideShow
apps/toys/Industrial
apps/toys/Shape3DToy
apps/toys/StretchyGrid
apps/toys/TouchSuite

tests/functional/*

tests/performance/VMPerformance

tools/*

While some of them might be useful, they aren't in their current form, and it is likely not worth the effort to fix them. They will be in the repo history if anyone really needs them.