* CalendarController.cs: removes useless spaces
* FrontOfficeApiController.cs: Makes the tex to pdf exceptions
available to the user interface, as part of the application process.
Cleans the using clauses.
* TexToPdfFormatter.cs: sets the filename as response header.
* Web.csproj: a new FormatterException, thrown when exit code of
texi2pdf is not null
8c4a6b9f19