Support reading and writing all LAS 3.0 features

LAS 3 specification: https://github.com/kinverarity1/lasio/blob/main/standards/LAS_3_File_Structure.pdf

Tasks:

• PR #327 Re-arrange LASFile.read so that header sections are parsed before touching any data sections (see comments in #1)
• Issue #265 Write a reader to handle comma separated data sections and strings -> numpy record array (refer to discussion in #1)
  • partly completed - see comment below
• PR #424: Ensure LASFile can handle different data types per CurveItem (possible partial solution PR in #424 which uses pd.DataFrame, although not pd.read_csv) - Update 26th April: resolved by #461
• Issue #446: Use an accelerated pandas reader e.g. pd.read_csv/pd.read_fwf where it is not needed for substitutions etc (refer to discussion in #1) - Update 26th April: being worked on in #452
• Issue #513: Compile set of real-world LAS 3 files to provide targets for tests and feature implementation.
• Issue #514: Finalize the API on LASFile for multiple linked Data + Definition sections (e.g. refer to discussion in this issue)
• Issue #515: Add format to HeaderItem
• Issue TBA Add association to HeaderItem
• Issue TBA: Figure out how to handle runs (needs discussion)

Update May 2020: I will start to sketch out a roadmap for how to achieve this. I think once this is reasonably well tested we can do a version 1 release.

Goals:

• Assume all LAS files are version 3 for parsing, even if they have a VERS code of 2.0. Only avoid this if we have to for performance.
• <strike>Aim to improve reading performance times, it’s really bad at the moment</strike>

<strike>Because I expect this work might require a broken branch for a while, let’s merge into the las3-develop branch if we need to.</strike>

[kinverarity1]

Update here: #452 was merged, so the next steps are making sure we can read comma-delimited data sections (#265) and then move on to the other LAS 3 issues which mostly relate to the header sections.

[kinverarity1]

FYI I’m happy to bring pandas in as a lasio requirement as part of this work. It’s probably time.