Update version to 8.8.1

New version (VowpalWabbit#2181)

* Fix style with clang-format (before releasing 8.8.0)

* Update verson.txt for release 8.8.0

* Revert "Fix style with clang-format (before releasing 8.8.0)"

This reverts commit df08035.

* succesfully ran clang-format

Incrementing version to 8.7.0.post1 for pypi

Update version to 8.7.0 (VowpalWabbit#1926)

* change semantics of lambda

* Fix style with clang-format (before releasing 8.7.0)

* Update verson.txt for release 8.7.0

* Revert "Fix style with clang-format (before releasing 8.7.0)"

This reverts commit 22ad628.

Change references from SolutionDir to ProjectDir

vw.vcxprojx has wrong references, they get exposed when
added to another Visual Studio Solution.

Fix model file parser for proper treatment of negative-valued options (…

…VowpalWabbit#1742)

* Fix model file parser for proper treatment of negative-valued options

The previous program options changes introduced an issue where models
  that have a stored value of the form '-' + '<digit>' will have the
  options merge logic incorrectly treat this value as a key and merge
  it in as "---<digit>", which then breaks the final parser pass.

The fix is to add a rule that option key identifiers cannot start from
  a digit (similar rules to variable identifiers), and treat it as a
  value when running the merge logic.

* Fix typos and misalignment in comments

* Fix formatting using clang-format

* I manually undid the merge of the four conditions in the check at
   parse_args.cc:1426, since it seems more readable with more whitespace

Merge branch 'master' of github.com:JohnLangford/vowpal_wabbit

Merge pull request VowpalWabbit#1521 from JohnLangford/cb_dm_semantics

Cb dm semantics

added autogen extra files

added autogen extra files