Merge branch 'inlinefont' closes gh-275

rename inline_rc to pylab_inline_rc

use config.Global.inline_rc to initialize matplotlib with the inline backend. Note that this will not be useful until the zmq kernel actually loads configuration from somewhere.

reorder stdlib imports closes gh-280

update docs to reflect XDG support, new ~/.config/ipython default

add `float_precision` trait to PlainTextFormatter * moved content of %precision into _float_precision_changed * %precision is now 2 lines that simply sets PTF.float_precision * added doctests for %precision * added tests for PTF.float_precision

tweak exceptions in %precision

add %precision magic closes gh-190

use XDG_CONFIG_HOME if available priority is: $XDG/ipython if both or neither exist $HOME/.ipython if it exists and $XDG/ipython does not exist closes gh-48 closes gh-246

tweak default font size for inline pylab backend xlabels on 6x4 log plots with 12pt font get cut off, so use 10pt, and increase bottom pad by 25%