Tesserocr

* Support new Tesseract 5 API (242)
* Support Windows build (250)
* GetBestLSTMSymbolChoices crash fix (241)
* Fallback to BMP instead of PNG
* Create pix from a BMP image bytes (156)

* Fix order of linker arguments (211)
* Fix memory leaks in GetComponentImages (213)

New features and enhancements:
* Support for `RowAttributes` method in LTRResultIterator (192)
* `SetImage`: use PNG instead of JPEG fallback (194)
* Replace `STRING::string()` by `c_str()` (197)
* Don't use assignment operator for TessBaseAPI (200)

Bugs fixed:

* `pixa_to_list` python3 segfault (176)
* `BlockPolygon` python3 segfault (185)

Tesseract v4 new API methods supported:
* GetBestLSTMSymbolChoices (147)
* BlanksBeforeWord (158)

Python 3.7 support release.