Byte-compile before batch-testing. General cleanup.

* *slime-*.el: require 'slime when loading and byte-compiling.
* slime-tests.el (slime-test-buffer-name): remove it
(slime-batch-test): no longer output to results file. Use
`ert-run-test-batch' when in batch mode.
* slime.el: Fix most compilation warnings and mispractices.
All function-calls
calls to cl.el are now correctly prefixed with "cl-". Require
'cl-lib.
* test.sh: Always byte-compiles code, -L skips.it. No longer
supports screen. No longer supports results and status files.
(cmd): don't set `debug-on-quit'.
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* README: Convert to markdown. Use Travis CI badge.