To Rearrange-Reader branch: Fix 5 tests : calculating number of data columns

[dcslagel]

This pull-request fixes the remaining previously broken tests on the rearrange-reader branch.

It also, removes python 2.7 from Travis-CI. Per #364, Python 2.7 won't be supported on the rearrange-reader branch.

This change adds parsing a data line with regexp_subs which fixes common errors in the data
(~A). It is added to reader.py::inspect_data_section(). inspect_data_section() is a new function
on the rearrange_reader branch that replaces the older "get data line length" steps.
This change is essentially pulling the regex_subs loop from the older steps and adding it to the
new inspect_data_section() function.

This change also accepts the n_columns from insect_data_section() if provisional_wrap is "NO".

API change:
This change adds regex_subs to inspect_data_section's parameter list:
from
inspect_data_section(file_obj, line_nos)
to
inspect_data_section(file_obj, line_nos, regexp_subs)

Here are the tests fixed with this change:

tests/test_null_policy.py::test_null_policy_runon_replaced_1
tests/test_null_policy.py::test_null_policy_runon_replaced_2
tests/test_null_policy.py::test_null_policy_runon_ok_1
tests/test_null_policy.py::test_null_policy_runon_ok_2
tests/test_write.py::test_write_sect_widths_12

Additional-Notes:

def inspect_data_section(file_obj, line_nos, regexp_subs) and def read_data_section_iterative(file_obj, line_nos, regexp_subs, value_null_subs) have a fair amount of code in common. A future issue/pull-request might work to
combine the common code.

Test and Coverage comparison with master branch

rearrange-reader + this change

204 passed, 1 skipped, 8 warnings

Name                   Stmts   Miss  Cover
------------------------------------------
lasio/__init__.py         13      2    85%
lasio/defaults.py         11      0   100%
lasio/examples.py         42     10    76%
lasio/excel.py            88     34    61%
lasio/exceptions.py        6      0   100%
lasio/las.py             364     54    85%
lasio/las_items.py       190     39    79%
lasio/las_version.py      34     22    35%
lasio/reader.py          420     91    78%
lasio/writer.py          160      9    94%
------------------------------------------
TOTAL                   1328    261    80%

master branch

221 passed, 2 skipped, 5 warning

Name                       Stmts   Miss  Cover
----------------------------------------------
lasio/__init__.py             13      2    85%
lasio/convert_version.py      20     20     0%
lasio/defaults.py             11      0   100%
lasio/examples.py             42     10    76%
lasio/excel.py                88     34    61%
lasio/exceptions.py            6      0   100%
lasio/las.py                 388     46    88%
lasio/las_items.py           190     31    84%
lasio/las_version.py          34     22    35%
lasio/reader.py              365     36    90%
lasio/writer.py              160      9    94%
----------------------------------------------
TOTAL                       1317    210    84%

Let me know if this change could be accepted (or rejected) or
needs some additional changes before being approved and merged.

Thank you,
DC

Edit note 2020-07-08: update coverage stats to remove my development files. This moves both total coverages from percents in the 60s to percents in the 80s.

[kinverarity1]

Great, thank you!

[dcslagel]

Thank you for the review and merge! :-)