Java interop

Interop lowers to the java: surface and runs on the interpreter and the JVM only -- the wasm backends reject java:. Class names resolve dotted as written, through :import, or through java.lang (the oracle's default-import list: the common throwables such as IllegalStateException are there, AutoCloseable is not). A string receiver answers the mapped core operation (a Lisp string is no host object), and .toString of any value that is no host object its str spelling, on every backend. A collection, keyword, symbol, ratio or atom answers its common methods (.count, .get, .contains, .getName, .numerator, .deref, ...) through the core functions on every backend, and refuses any other method by name (.name). str of a host object answers its toString. Printed readably (prn, pr-str, inside a collection str spells), a Java List is a vector when it is RandomAccess (ArrayList) and a list otherwise (LinkedList), a Map a map and a Set a set, in the collection's own order, like the oracle; any other host object, and every one under println/print, shows #<java C> (the oracle's #object[...] without the hash and toString), except a class object, which prints its name. A construction of a throwable class that carries only a message and a cause is an exception, and .getMessage/.getLocalizedMessage/.getCause of an exception (a caught runtime error included) answer from it, on every backend. An exception a member throws is the host's own, which a catch takes by its class (try); an exception the program built, passed to a member, is a host exception of its class (Deviations).