Supersede TSPLIB

[leonlan]

A long-term goal is to supersede the TSPLIB95 specification. See here.

Note to self:

• DISPLAY_DATA_TYPE: NO_DISPLAY means that the array is unformatted.

[leonlan]

I checked (reading LKH-3 instances) today. Some of the LKH instances have TSPLIB95 specifications that are not yet supported (see #94) so not all of these instances can be read without issues.

Originally posted by @leonlan in #89 (comment)