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