Add extended globbing (extglob) to copyFiles

[HuskyNator]

Add extended globbing to the copyFiles parameter.

This allows creating simpler and more effective globs.
One simple example is given below.

---

Example;
Assuming one wants to copy all files at root to a build folder, a simple "*" will not work.
The following will copy the current project to the build folder, which itself will do the same (etc etc), each time coppying itself. (no clue what the limit is)

dub.json:

...
"copyFiles": ["*"],
"targetPath": "build",

Solution eg.: !(dub.json)