Preview release 0.3.0

• Added an initial pass at a Log Information Standard 79 (LIS79) reader. Like
  the DLIS reader, the new LIS reader is mainly implemented in C/C++ with
  python bindings on top. The reader is not feature complete at this point. But
  it can read most curves, with a few exceptions (see the docs of
  dlisio.lis.curves). Basic metadata such as LIS Header/trailer Records (RHLR,
  RTLR, THLR, TTLR, FHLR, FTLR) can also be read. Support for more complex LIS
  Records such Information Records is not yet added. The LIS reader
  resides in the python submodule dlisio.lis.
• The python module is restructured to accommodate the new LIS reader. Most
  notably, all DLIS related functionality is moved to the submodule
  dlisio.dlis. I.e. this release breaks the main entry point of dlisio
  dlisio.load which from this release and onwards is moved to
  dlisio.dlis.load. For a full overview of the restructuring see
  commit #736d545.
• The documentation on readthedocs_ has been given an overhaul to fit the new
  module structure and LIS documentation is added.
• Added support for DLIS NOFORM objects.
• Better debug information for broken DLIS files.
• Better error message when passing a directory as path to dlisio.dlis.load.
• Nicer error message when failing to construct datetime objects due to invalid
  dates in the file.
• Added support for python 3.9
• Dropped support for python 3.5
• Restructuring the C/C++ core of dlisio, please refer to the git log for a
  full overview of the restructuring.
• The C and C++ targets are merged into one target dlisio, and
  dlisio-extension ceased to exist.