Duplicated SPE readers in codebase

There are two instances of SPE readers in the codebase:

• @spe\private\get_spe_matlab.m
• @loader_ascii\private\get_spe_matlab_.m

The functions are pretty similar, the @loader_ascii version seems to have built upon a copy of the @spe version.

We should remove one version and replace any usages with the other version. My first instinct is that the @spe version should be removed, but part of this ticket will be to decide which reader to keep and which to replace.

Outputs:

• There should only be one SPE file reader

CM 17.10.23 - UPDATE
the specific names mentioned here are no longer present but similar ones without matlab are.
To be reviewed and prioritised.