Added the "Quick Export" Command

[rtfmkiesel]

Added the quick export command, which enables a faster export. (no filename selection and faster type selection via window.showQuickPick)

I mainly did this, because I was annoyed to always go into the settings to change the export type from PDF to HTML and vice versa.

Maybe addresses #311

Obviously, it would also be possible to add quick export commands for every single type, which would make it one more step faster.

[rtfmkiesel]

Any chance of this getting merged? @yhatt

[yhatt]

I think it requires re-considering the whole of commands to make clear for users.

• Export slide deck (Quick export)
  • Execute exporting, that it was known as "Quick export" in original issue and this PR.
  • Create the output next to the current file.
    • If the target file was not saved, this command has the same meaning as "Export slide deck as..."
  • The format is using specified in markdown.marp.exportType preference. The step to choice the format may not need.
• Export slide deck to specified format...
  • Execute quick export, but ask the file format before.
• Export slide deck as...
  • Execute exporting that it has current behavior.
  • Always open save dialog, and ask where to export.
  • User can choice the format in the save dialog.

[rtfmkiesel]

Going to start from scratch, taking your requirements into consideration.