hdfview

Fix issue where scalar datasets had no radio button selected in Open As window

Fix issue where HDFView tries to dispose a null font

Add double-click expand/collapse functionality for TreeView

Fix null pointer exception when answering 'no' to replacing file when creating new file of same name as existing file

Add changing of link target in right-side showMetaData panel

Add support for user to type in custom file location for external link target file. Pressing enter loads the file and its objects