Fix bug #351664 by adding try/catch around the code that attempts to load
Fix bug #351664 by adding try/catch around the code that attempts to load

	* Tomboy/Plugins/ExportToHTML.cs: Fix bug #351664 by adding
	try/catch around the code that attempts to load the exported note
	into a web browser.  If opening a web browser fails, a dialog will
	alert the user that the note was exported successfully.  Also, the
	export preferences are not saved unless the note is exported
	successfully.

oluc/tomboy,tomboy-notes/tomboy,rmayr/privatenotes-tomboyaddin,grepory/tomboy,rmayr/privatenotes-tomboyaddin,MatteoNardi/Tomboy,rotty3000/tomboy,tomboy-notes/tomboy,grepory/tomboy,MatteoNardi/Tomboy,rotty3000/tomboy,oluc/tomboy,grepory/tomboy,MatteoNardi/Tomboy,oluc/tomboy,rmayr/privatenotes-tomboyaddin,tomboy-notes/tomboy,oluc/tomboy,grepory/tomboy,MatteoNardi/Tomboy,grepory/tomboy,tomboy-notes/tomboy,oluc/tomboy,rotty3000/tomboy,rmayr/privatenotes-tomboyaddin,rotty3000/tomboy,MatteoNardi/Tomboy,rotty3000/tomboy,rmayr/privatenotes-tomboyaddin,MatteoNardi/Tomboy,tomboy-notes/tomboy,oluc/tomboy