Add CMU Graphics Lab Motion Capture dataset

## Adding a Dataset
- **Name:** CMU Graphics Lab Motion Capture database
- **Description:** The database contains free motions which you can download and use. 
- **Data:** http://mocap.cs.cmu.edu/
- **Motivation:** Nice motion capture dataset

Instructions to add a new dataset can be found [here](https://github.com/huggingface/datasets/blob/master/ADD_NEW_DATASET.md).

Labels: name: dataset request

name: vision

This dataset has files in ASF/AMC format. [ The skeleton file is the ASF file (Acclaim Skeleton File). The motion file is the AMC file (Acclaim Motion Capture data). ]  

Some questions : 
1. How do we go about representing these features using datasets.Features and generate examples ?
2. The dataset download link for ASF/AMC files does not have metadata information, for eg : category and subcategory information. We will need to crawl the website for this information. The authors mention "Please don't crawl this database for all motions." Can we mail the authors for this information ?
The dataset structure is as follows : 
```
subjects
	- 01
		- 01_01.amc
		- 01_02.amc
		.
		.
		.
		- 01.asf
	- 02
		- 02_01.amc
		- 02_02.amc
		.
		.
		.
		- 02.asf
```
There is no metadata regarding the category, sub-category and motion description.

Need your inputs. @mariosasko / @lhoestq  
Thank you.


Hi @dnaveenr! Thanks for working on this!

1. We can use the `Sequence(Value("string"))` feature type for the subject's AMC files and `Value("string")` for the subject's ASF file (`Value("string")` represents the file paths) + the types for categories/subcategories and descriptions.
2. We can use this URL to download the motion descriptions: http://mocap.cs.cmu.edu/search.php?subjectnumber=<subject_number>&motion=%%%&maincat=%&subcat=%&subtext=yes where `subject_number` is the number between 1 and 144. And to get categories/subcategories, feel free to contact the authors (they state in the FAQ they are happy to help) and ask them if they can provide the mapping from categories/subcategories to the AMC files to avoid crawling. You can also mention that your goal is to make their dataset more accessible by adding its loading script to the Hub.

The AMC files are also available in the tvd, c3d, mpg and avi formats (the links are in the [FAQ](http://mocap.cs.cmu.edu/faqs.php) section), so it would be nice to have one config for each of these additional formats. 

And additionally, we can add a `Data Preprocessing` section to the card where we explain how to load/process the files. I can help with that.

Hi @mariosasko ,

1. Thanks for this, so we can add the file paths.
2. Yes, I had already mailed the authors a couple of days back actually, asking for the metadata details[ i.e category, sub-category and motion description] . They are yet to respond though, I will wait for a couple of days and try to follow up with them again. :) Else we can use the workaround solution.

Yes. Supporting all the formats would be helpful. 

> And additionally, we can add a Data Preprocessing section to the card where we explain how to load/process the files. I can help with that.

Okay. Got it.