Raise error when reading Solomon instance without specifying instance format about vrplib HOT 3 CLOSED

We could do something like np.loadtxt:

https://github.com/numpy/numpy/blob/8cec82012694571156e8d7696307c848a7603b4e/numpy/lib/npyio.py#L1061-L1068

from vrplib.

In #76 we managed to find a way to verify if an instance is in VRPLIB format or not. We can do the same for Solomon instances. The Solomon instances have a fixed file format:

<NAME>

VEHICLE
NUMBER	CAPACITY
<number> <capacity>

CUSTOMER
CUST. NO 	XCOORD.	YCOORD.	DEMAND	READY TIME	DUE DATE	SERVICE TIME
<data row 1>
...

• We ignore all empty lines.
• Then we check if the first line contains "VEHICLE"
• We check that the second line contains "NUMBER" and "CAPACITY"
• We check that the third line contains two integer values
• We check that the fourth line contains "CUSTOMER"
• The fifth line contains the customer header names, but these are inconsistent in number of spaces. For example, sometimes SERVICE TIME is used and sometimes SERVICE TIME is used. So I'm not sure how to check this.

from vrplib.

Closed by #83.

from vrplib.