Add ability to interpret path and reference from full url

[wilvk]

As per issue #6 , it can be confusing when looking at a github web url and translating it into the format -u -d -r

for example:

from:

https://github.com/EsotericSoftware/spine-runtimes/tree/1c717e2d4402e69dd6fe81bf1bb3d8d6d0a58447/examples

to:

githubdl -u "https://github.com/EsotericSoftware/spine-runtimes" -d "examples/raptor" -r 1c717e2d4402e69dd6fe81bf1bb3d8d6d0a58447

this should be detected and taken care of from the url provided.

[Justsoos]

and how about "blob" uri?
like https://github.com/zhangn1985/ykdl/blob/620b98060dae5d3a8c00fb46751488e4fddea7a3/ykdl/extractors/douyu/live.py

[wilvk]

@Justsoos there's probably a few valid formats of url that need to be considered.

[Justsoos]

http://kinolien.github.io/gitzip/
could do all, and it is open source by JavaScript.
btw, the top post miss a child path "raptor" on first command, and dl results have a wrong depth of double "raptor"

$ tree examples/
examples/
└── raptor
    └── raptor
        ├── export
        │   ├── raptor-pma.atlas
        │   ├── raptor-pma.png
        │   ├── raptor-pro.json
        │   ├── raptor-pro.skel
        │   ├── raptor.atlas
        │   └── raptor.png
        ├── images
        │   ├── back-arm.png
...

[wilvk]

that's nice. they serve different purposes. use the -d switch to specify the directory.