Filechooser setcurrentdir

This pull request makes the file choosers for FileFormField and for the 'load properties' action use a starting directory more convenient for the user.

When the file chooser is called for a field with a relative pathname:
* for load properties, use resourceRoot or project path parent 
* for FileFormField, use currentDirectory if set, otherwise projectRoot if set, otherwise system property "user.dir"

When the file chooser is called for a field with an absolute pathname, set the current directory to the parent of that pathname, if it is a file, or to the pathname itself if it is a directory.

In all cases, if the currentDirectory to set on fileChooser does not exist, we try up the (logical) directory hierarchy until we get one that exists, falling back on the system property "user.dir" is none is found.