* Track the last used path for the current session.
* Set focus back to OK button after wxFilePickerCtrl button is pressed to change file path
and/or file name so next return key press fires OK event.
* Use default dialog size to let the sizers set initial dialog size.
* Add spacer to improve layout when resizing dialog.
* Adds a "Grid Reference Point" to the VRML export; this allows a user to specify the (X,Y) coordinate which will be the origin point on the output
* Adds a "Grid Reference Point" to the IDF export; this is similar in purpose to the corresponding VRML export feature.
* Improve VRML export dialog lay out.
* Make the OK button the default action in the export dialog.
* Make 3D model export work correctly and avoid redundant file copies.
* Fix embedded path separators in wrl files on windows.
* Fix absolute model file path creation in wrl files.
* Clean up VRML export code.
File "rules" has instructional text as comments near top.
2) Convert all text files in repo to LF line ending form.
Any checkout done with "rules" in play will convert the working
tree to native line ending, while keeping repo as LF line ending.