Installs pretty exceptions, then delegates to clojure.main/main.

Installs an override that outputs pretty exceptions when caught by the main REPL loop. Also, overrides
`clojure.repl/pst`, `clojure.stacktrace/print-stack-trace`, `clojure.stacktrace/print-cause-trace`.

Extends `clojure.core/print-method` for type Throwable to print a blank line followed by the
formatted exception. This allows an expression that evaluates to an exception to be printed prettily,
but more importantly, ensures that in `clojure.test/is` a failed `thrown-with-msg?` assertion
prints a formatted exception.

Finally, installs an [[uncaught-exception-handler]] so that uncaught exceptions in non-REPL threads
will be printed reasonably.

Caught exceptions do not print the stack trace; the pretty replacement for `pst` does.

Replacement for `clojure.stacktrace/print-stack-trace` and `print-cause-trace`. These functions are used by `clojure.test`.

Used as an override of `clojure.repl/pst` but uses pretty formatting.  Output is written to `*err*`.

A replacement for `clojure.main/repl-caught` that prints the exception to `*err*`, without a stack trace or properties.

Returns a reified UncaughtExceptionHandler that prints the formatted exception to `*err*`.