Fix minor documentation issues
Use custom replacement for table_get_column

As explained in the comment MAD-X r4777 fixes the handling of integer
columns in the table_get_column function. As it seems overkill to
require a new MAD-X version for a minor patch, the function is replaced
with a Cython snippet inside cpymad for now.

When we require a newer version of MAD-X sometime in the future, THIS
COMMIT MAY BE REVERTED.

There is one additional benefit to the replacement code though: The
ability to raise exceptions with more detailed descriptions on what went
wrong.
Add support for integer columns in tables

This requires either MAD-X revision 4777 or the code added in 00281a4.
Add madx.chdir to change current working directory
Change directory when doing CALLs by default

I think this will more likely match any user expectations when CALLing
files with CALL instructions using relative pathes inside them.
Enable RPC of functions in arbitrary modules

This was originally thought as a generalization to make 'os' importable
in the remote process in order to perform ChangeDirectory operations.

Now, I decided to add 'chdir' and 'getcwd' to 'cpymad.libmadx' for
convenience, so this commit is not a necessity for the moment. But I
still believe, that it can prove useful for third party tools that need
to perform special setup (e.g. in MadGUI).
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 #50 from pymad/integer-array-columns

support integer arrays in tables
Merge pull request #51 from coldfix/change-cwd

Add function to change directory in the remote process
Merge pull request #53 from coldfix/update-install-instructions

Update install instructions and recommendations