BF: rudimentary docstring for mvpa2.datasets.sources

Detected thanks to
http://nipy.bic.berkeley.edu/builders/pymvpa-py2.7-osx-10.8/builds/1/steps/shell_3/logs/stdio
BF: process information is N/A on non-Linux, thus bad to rely on it for the baisc test of wtf()
BF: uglyish workaround for absent /status parsing on non-Linuxes
ENH: externals.exists -- allow to raise an arbitrary exception
BF: raise ImportError instead of RuntimeError if checked when importing module

I hope it would make nose react saner, see:
http://nipy.bic.berkeley.edu/builders/pymvpa-py2.7-osx-10.8/builds/1/steps/shell_3/logs/stdio
ENH: allow suite_stats get stats from any scope + test that we get entries of every type

for some strange reason on OSX buildbot datasets.source also became available
in a globals() which allowed to catch it missing a docstring.  It doesn't happen
on Linux'es and I was trying to achive the same failure by looking into the scope
of imported suite -- but could not replicate thus that code was left commented out
BF: externals.exists -- one more location where to change type of exception to given one
Changing the exception to ImportError didn't help - so import submodules conditionally
BF: condition import in plots on matplotlib

Otherwise fails nose test build
http://nipy.bic.berkeley.edu/builders/pymvpa-py2.7-osx-10.4-ppc/builds/4/steps/shell_3/logs/stdio
BF: smlr.c -- move declarations up in the function, surround if's then in {}

With hope to avoid FTBFS on windows:
http://nipy.bic.berkeley.edu/builders/pymvpa-py2.6-xp/builds/4/steps/shell_2/logs/stdio
TST: MVPA_TESTS_WTF controls printing of wtf() upon completion + removed spurious prints in test_wtf
TST: Apparently fixing parameters for d.fit doesn't work on scipy 0.8.0 on OSX, so skipping

http://nipy.bic.berkeley.edu/builders/pymvpa-py2.6-osx-10.5-ppc/builds/4/steps/shell_3/logs/stdio
Report mvpa2  path and sys.path while building docs

to figure out WTF with
http://nipy.bic.berkeley.edu/builders/pymvpa-doc-builder/builds/1/steps/shell_4/logs/stdio
BF: do not link smlr.so against libm on Windows
BF(win32): bring back initsmlrc for Python < 3
BF(TST): mkstemp opens a file. if we are to use the name only -- must close first

otherwise exotic platforms like Windows would scream out loud:
http://nipy.bic.berkeley.edu/builders/pymvpa-py2.6-xp/builds/12/steps/shell_3/logs/stdio
ENH(TST): print wtf() to stderr so to not interleave with nose errors
BF(TST): opening already opened files would not work on windows -- so close it first

See http://nipy.bic.berkeley.edu/builders/pymvpa-py2.6-xp/builds/14/steps/shell_3/logs/stdio
BF(TST): close file before its remove (for your lovely Windows)
Merge branch 'master' of https://github.com/PyMVPA/PyMVPA