Collected minor fixes

• Make Indent/Un-Indent optional in the WiPy version, to allow all variants to get compiled w/o running out of memory. Even the, it's not Undo-able. The final code saving is just a few hundred bytes, so it's still not clear to me why these few extra lines dont't fit.
• Making the MOUSE support a seperate option, which can also be chosen for WiPy
• Added a flag to pye2 such that it supports both vertical cursor movement types
• Removed the extra indent after ':' as the last char on the line. More confusing than helpful.
• If open file names a directory, the list of files is loaded to the edit buffer. Doing that, replace the name '.' by the result of os.getcwd(), avoiding error 22 of stat() call on PyBoard and WiPy
• Ctrl-V in line edit mode inserts the first line of the paste buffer
• Moved error catching one level up to the function pye(), catching load-file errors too.
• Fixing a glitch which added an extra line when un-doing the deletion of all lines
• use uos.stat with micropython, since os.stat is not supported on linux-micropython