* Remove ENVIRONMENT_VARIABLE_CHAR_VALIDATOR::OnChar() because it was skipping
the filtering of the first character. Not sure what was going but this seemed to fix the issue.
* Added environment variable name test to DIALOG_ENV_VAR_CONFIG::TransferDataFromWindow
because apparently validators do not get called in wxGrids even whe the extend window style
wxWS_EX_VALIDATE_RECURSIVELY is set.
* Set the default button using wxFormBuilder since the OK button is not part of a wxStdDialogButtonSizer.
* Minor improvements to the HTML help dialog.
* Fix assertion when calling HTML help dialog. Apparently any dialog derived from DIALOG_SHIM must
have a KIWAY top level window as a parent.
* Create new dialog to edit environment variables.
* Add helper class ENV_VAR_ITEM to manage environment variable values and
if they were defined externally.
* A path configuration dialog access to KiCad, CvPcb, Pcbnew, and Footprint Editor
window menus.
* Add validator for environment variables.
* Refresh canvas when user cancels edits so that the discarded sheet is
cleared from the schematic.
* Add file name validation to the sheet properties dialog to prevent
illegal file name characters from being entered into the text control.
* Rename FOOTPRINT_NAME_VALIDATOR to FILE_NAME_CHAR_VALIDATOR for clarity.
* Replace illegal file system characters when reading legacy libraries to
prevent FPID parsing errors and allow saving to PRETTY file format.
* Create validator to filter illegal file system characters from footprint
name text edit controls to prevent issues when saving to PRETTY file format.
* Add missing source file licenses and some minor coding policy fixes.
jean-pierre charras
Wayne Stambaugh