ParameterFilter fixes

The script block passed to the -ParameterFilter parameters on Mock and Assert-MockCalled is now executed in the test script's scope.  To prevent errors when the parameter filter is being evaluated in some cases, Strict Mode is disabled within that block (but left alone otherwise).s
Direct test execution fix

Corrects a bug that occurs when a test script is dot-sourced into the global scope.  In that situation, mocks can wind up being executed by modules that were not intended to see the mock (including Pester itself.)
Merge branch 'ParameterFilterFixes' into MyBetaUpdates