Fix minor documentation issues
Update recommendation to use *static* library on windows

Currently, we have only one Cython file linking to MAD-X. In this case
static linkage makes the most sense, since one doesn't have to care
about putting the runtime libraries in the correct folders.
Mention --rpath and --madxdir options to set runtime-lib path
Raise OSError when .c source file is missing

This error is much more explicit and the user will probably not need to
consult the online installation instructions anymore.
Merge pull request #53 from coldfix/update-install-instructions

Update install instructions and recommendations