Started implementing "better" reading

read_ring from ringreader now takes max_items and nread
and returns raw_data. This breaks all other modules.
Next step is to take sta as parameter
Standard name for setup script
more ignores
freeing raw_data pointer
Passing kwargs to module_read function
added support for max_traces and sta

max_traces is the maximum number of traces
of read, and sta is a parameter to filter
the station name to read. ringreader interface
got rolled back. This is handled at module level
Wrote more tests

Test max_trace functionality
and sta filtering functionality
Merge branch 'master' of https://github.com/serpulga/python-ew