Crash

================

- bugfix: crash exited immediately with an exception if a query result
contained an object or array

- the size of the history file is now limited to 10000 lines

- stdin is no longer read completely into memory

================

- SQL statements passed in via the --command switch take precedence over stdin

================

- bugfix: crash exited immediately with an exception if a query result
contained two or more equal field names

================

- bugfix: if crash was started while one of the specified hosts was
not available crash exited immediately

================

- updated crate-python to 0.9.3 to fix import errors

================

- added sphinx scripts to generate documentation

- minor documentation improvements