Make path short in case of big path and small window

[anki-code]

/long/long/long/long/long/long/path -> .../long/path

Start lines -

xontrib-prompt-bar/xontrib/prompt_bar.py

Lines 151 to 152 in fce5308

	lpc = _format_sections(_LEFT)
	rpc = _format_sections(_RIGHT)

[anki-code]

Example:

$PROMPT_FIELDS['cwd4'] = lambda: str(Path(*Path(__xonsh__.env['PROMPT_FIELDS']['cwd']()).expanduser().parts[-4:]))
$XONTRIB_PROMPT_BAR_LEFT = '{hostname#nolocal}{user#nolocal}{cwd4#accent}'
xontrib load prompt_bar