Added CLI argument support

[MaverickMartyn]

I added support for setting the LOD path, output path and road type using commandline arguments.
The arguments also include an -autorun parameter, to automatically start the generation, and a -clear-output-on-generate parameter. The path arguments support both absolute and relative paths.
All the parameters are documented in the README.md file.

This is useful for launching from mod managers. I for one, use my own build with a portable Mod Organizer 2 instance.
That way, I don't need to remember or even update the paths. All it takes to update the roads is executing the shortcut, if you point the output to a mod folder.

Here's is an example of how I use it: ACMOS Road Generator.exe -autorun -clear-output-on-generate -l:"../xLODGen/xLODGen_Output" -o:"../ACMOS_Output".

Maybe there's a better name for the -clear-output-on-generate argument, since it's a tad long.

[MaverickMartyn]

@DoubleYouC Is this still being maintained?
I don't mean to rush you. I'm just curious.