import: make patch apply if run in subdir fix is same as for mq patch. patch apply code should be merged.

hgcommand.vim: requirements & doc self-install more consistent; cosmetics Check for availability of builtin system(). Set 'compatible' while sourcing script. File operation during doc self-install: Escape spaces in ex-commands. Use quotes in system calls. Incremented revision number(s). Size of patch is due to cosmetic cleanups: Removal of spaces at line endings. <SID>Prefix to functions when called.