Port USFM code from Machine up to commit c93f8dc (#118)

* port commit afc6328, fix usfm parsing/generation issues

* port commit 3182ff2, fix error on terms id duplication

* port commit 8efc011, skip parsing excluded books when preprocessing

* port commit 4e88953, fix missing last verse

* port commit ceb586c, remove obsolete handling of \d marker

* port commit 1011777; fix 2, 2a, 2b verse merging

* port commit 2469d89, fix sillsdev/serval#424

* port commit 385213e, fix sillsdev/serval#424

* port commit 2659e19, usfm nonverse multichapter

* port commit 3911dd6, extend manual test to process multiple projects including zipped projects

* port commit cd90626, fix USFM parsing bugs

* port commit a15d24e, fixes sillsdev/serval#449

* port commits from PR #233, use terms localizations

* call the horizontal position 'character'

* address review feedback

* move memory_paratext_project_terms_parser.py to tests folder

* port commit 7a819ed, remove duplicate test

.ignore

@@ -0,0 +1,3 @@
+!tests/SIL.Machine.Tests/Corpora/TestData/usfm/source/*
+!tests/SIL.Machine.Tests/Corpora/TestData/usfm/target/*
+!tests/SIL.Machine.Tests/Corpora/TestData/project/*