ARROW-7: Add barebones Python library build toolchain

This patch provides no actual functionality; it only builds an empty Cython extension that links to libarrow.so. I will hook this into Travis CI at some later time.

I have adapted a limited amount of BSD (2- or 3-clause) or Apache 2.0 3rd-party code (particularly the cmake/Cython integration) to bootstrap this Python package / build setup in accordance with http://www.apache.org/legal/resolved.html. I have noted the relevant copyright holders and licenses in `python/LICENSE.txt`. In particular, I expect to continue to refactor and reuse occasional utility code from pandas (https://github.com/pydata/pandas) as practical.

Since a significant amount of "glue code" will need to be written to marshal between Arrow data and pure Python / NumPy / pandas objects, to get started I've adopted the approach used by libdynd/dynd-python -- a C++ "glue library" that is then called from Cython to provide a Python user interface. This will allow us to build shims as necessary to abstract away complications that leak through (for example: enabling C++ code with no knowledge of Python to invoke Python functions). Let's see how this goes: there are other options, like Boost::Python, but Cython + shim code is a more lightweight and flexible solution for the moment.

Author: Wes McKinney <[email protected]>

Closes #17 from wesm/ARROW-7 and squashes the following commits:

be059a2 [Wes McKinney] Nest arrow::py namespace
3ad3143 [Wes McKinney] Add preliminary Python development toolchain

cpp/src/arrow/CMakeLists.txt

@@ -20,6 +20,7 @@ install(FILES
   api.h
   array.h
   builder.h
+  field.h
   type.h
   DESTINATION include/arrow)
 

cpp/src/arrow/table/CMakeLists.txt

@@ -36,6 +36,9 @@ SET_TARGET_PROPERTIES(arrow_table PROPERTIES LINKER_LANGUAGE CXX)
 
 # Headers: top level
 install(FILES
+  column.h
+  schema.h
+  table.h
   DESTINATION include/arrow/table)
 
 ADD_ARROW_TEST(column-test)

python/.gitignore

@@ -0,0 +1,37 @@
+thirdparty/
+CMakeFiles/
+CMakeCache.txt
+CTestTestfile.cmake
+Makefile
+cmake_install.cmake
+build/
+Testing/
+
+# Python stuff
+
+# Editor temporary/working/backup files
+*flymake*
+
+# Compiled source
+*.a
+*.dll
+*.o
+*.py[ocd]
+*.so
+.build_cache_dir
+MANIFEST
+
+# Generated sources
+*.c
+*.cpp
+# Python files
+
+# setup.py working directory
+build
+# setup.py dist directory
+dist
+# Egg metadata
+*.egg-info
+# coverage
+.coverage
+coverage.xml