Added flags

usage: sh pma-update.sh [-hvf] [-r version]
-h		show help
-v		output all warnings
-f		force download, even if this version is installed already
-r version	choose a different version than the latest.
Typo
Added .4 files
Typo again :/
Revert "Typo again :/"

This reverts commit 0f5887cd44a12a9e65c87a67940de199552282da.
Better readability
Long flags and compatibility

Added long flags (—help) and dash compatibility
Merge pull request #4 from stefansl/dev

New version with flags. See README or ./pma-update.sh -h for options