Maintanability: Remove deprecated io classes

[juarezr]

Context

• After Petl use fsspec #494 landed in v1.6.0, petl started using fsspec for handling read and writing from/to remote servers and cloud filesystems.
• Before there were some classes for dealing with compression and SMB.
• But with fsspec they become duplicated code.
• We have these choices for this code:
  • Remove it and require fsspec for this functionality
  • Make it private and use it as a fallback when one does not want to add a dependency to fsspec. So one need to make it clear in docs.