[Suggestion] Additional command line flags for modpack generator

[dj3520]

I'd like to suggest 2 additional command line flags to the modpack manifest generator to allow a bit of extra usability, one for ignoring the url.txt files to allow debugging or for a LAN party configuration to quickly be made in conjunction with my second suggestion. The second would only update the manifest and not output the files, allowing a change in the configuration to be easily done (change optional features and download links, etc.)

The second could already be done I suppose on linux systems by outputting to /dev/nul but I primarily use Windows machines. Perhaps they could be --nooutput and --update-only though other opinions are welcome.

[sk89q]

For #1: use -Dcom.skcraft.builder.ignoreURLOverrides=true before -cp

[dj3520]

before cp? and does it need double dashes?

[sk89q]

It needs to be before the main class more specifically. Single dash.