Port FlatBuffers to Python.

Implement code generation and self-contained runtime library for Python.

The test suite verifies:
  - Correctness of generated Python code by comparing output to that of
    the other language ports.
  - The exact bytes in the Builder buffer during many scenarios.
  - Vtable deduplication correctness.
  - Edge cases for table construction, via a fuzzer derived from the Go
    implementation.
  - All code is simultaneously valid in Python 2.6, 2.7, and 3.4.

The test suite includes benchmarks for:
  - Building 'gold' data.
  - Parsing 'gold' data.
  - Deduplicating vtables.

All tests pass on this author's system for the following Python
implementations:
  - CPython 2.6.7
  - CPython 2.7.8
  - CPython 3.4.2
  - PyPy 2.5.0 (CPython 2.7.8 compatible)

python/flatbuffers/packer.py

@@ -0,0 +1,28 @@
+"""
+Provide pre-compiled struct packers for encoding and decoding.
+
+See: https://docs.python.org/2/library/struct.html#format-characters
+"""
+
+import struct
+from . import compat
+
+
+boolean = struct.Struct(compat.struct_bool_decl)
+
+uint8 = struct.Struct("<B")
+uint16 = struct.Struct("<H")
+uint32 = struct.Struct("<I")
+uint64 = struct.Struct("<Q")
+
+int8 = struct.Struct("<b")
+int16 = struct.Struct("<h")
+int32 = struct.Struct("<i")
+int64 = struct.Struct("<q")
+
+float32 = struct.Struct("<f")
+float64 = struct.Struct("<d")
+
+uoffset = uint32
+soffset = int32
+voffset = uint16