Problem: More functions can be used as methods.
Solution: Make various functions usable as a method. Make the window
command test faster.
ce90e36f59
test_* functions in the patch are N/A as they modify internal state.
Include test changes for test_ignore_error and test_feedinput (though they aren't run).
Other changed tests were excluded from previous patches, except test_termcodes.vim, which hasn't
been ported yet.
39776d1a65
