python packages: move all things python under lang/python

I admit this may be be a bit aggressive, but the lang
folder is getting cluttered/filled up with Python, PHP, Perl,
Ruby, etc. packages.

Makes sense to try to group them into per-lang folders.

I took the Pythons.

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>

lang/python/python-packages/README.md

@@ -0,0 +1,72 @@
+This package allows users to package python modules without creating package
+Makefiles for each individual module and their dependencies.  It provides a
+way making packaging python packages faster and may also facilitate the process
+of developing Makefiles for new python packages
+
+This is a raw DEVEL only package.  Using it may entail a lot of implementation
+details and you may need to resolve target dependencies and package details on
+your own
+
+- Third party python packages may depend on features not included in e.g.
+  python-light
+- Some python modules may require host install of another module to progress,
+  e.g. target cryptography requires host cffi
+- Some python modules have external C library dependencies, e.g. pyOpenSSL
+  requires openssl libs
+- Some packages may have an autoconf configure script whose arguments we
+  cannot control with pip and has to be passed on (hacked) by overriding some
+  environment variables
+
+## How it works
+
+1. Install host modules required for building target modules
+2. Install each target module to separate directories
+3. Install another copy of modules for cleanup purposes to make list of
+   installed files to be removed from target modules installed in step 2
+
+Why should it be so
+
+1. Installing target cryptography requires host installation of cffi module
+2. cryptography requires setuptools and pip will install its own copy with
+   --ignore-installed.  When PACKAGE_python-setuptools is also selected, opkg
+   will complain of data file clashes if it was not removed here.
+
+Pip will handle dependency requirements of python modules, but external
+dependencies like c libraries has to be prepared by the build system.  The
+issue is that there is currently no way to express such dependencies, thus may
+cause build failure, e.g. pycrypto requires the presence of libgmp to build
+successfully.
+
+## Tips
+
+If something goes wrong, we can add additional arguments to pip command
+line to check the detailed build process.  Some useful arguments may be
+
+- -v, for verbose output.  Repeat this option if the current level of
+  verbosity is not enough
+- --no-clean, for preserving pip build dir on build failure
+
+## Examples
+
+tornado (python-only module)
+
+	CONFIG_PACKAGE_python-packages=y
+	CONFIG_PACKAGE_python-packages-list="tornado==4.4.2"
+
+cryptography (requires installation of host modules and cleanup on target modules)
+
+	CONFIG_PACKAGE_python-packages=y
+	CONFIG_PACKAGE_python-packages-list-host="cffi"
+	CONFIG_PACKAGE_python-packages-list="cryptography"
+	CONFIG_PACKAGE_python-packages-list-cleanup="setuptools"
+
+pycrypto 2.7a1 (python module with autoconf configure script; depends on
+libgmp; broken wmmintrin.h).  2.6.1 does not work because of a flaw in
+the setup.py hardcoding host include directory
+
+	CONFIG_PACKAGE_libgmp=y
+	CONFIG_PACKAGE_python-packages=y
+	CONFIG_PACKAGE_python-packages-list="https://github.com/dlitz/pycrypto/archive/v2.7a1.tar.gz"
+	CONFIG_PACKAGE_python-packages-envs="ac_cv_header_wmmintrin_h=no build_alias=$(GNU_HOST_NAME) host_alias=$(GNU_TARGET_NAME) target_alias=$(GNU_TARGET_NAME)"
+	CONFIG_PACKAGE_python-packages-extra-deps="libgmp.so.10"
+