direct IFn invoke for keywords
remove flooring from nth logic, not present in Clojure, significant perf
boost for nth
add node header further down
more defrecord benchmarks
add name test for keywords
CLJS-635: ensure that rseq of empty collections always returns nil
Fix property-accessor in clojure.browser.repl after the namespace syntax change in cljs
Update property-accessor style in clojure.reflect
CLJS-634: do not call getPath on a null value.
CLJS-628: *cljs-file* not bound when compiling to stdout
CLJS-471: prevent empty regexps from causing compiler errors

Depending on the JS vm being used, empty regexes will print as
either #"" or #"(?:)" (the latter being emitted by those with a
webkit heritage AFAICT).
CLJS-632: use tools.reader's *alias-map* for tracking aliases instead of Clojure namespaces:

* updated tools.reader to 0.7.10
* renamed `:uses-macros` and `:requires-macros` keywords used internally
  in the analyzer to be imperative, matching `ns` usage
CLJS-638: Keyword invoke is inconsistent with clojure

Keyword -lookup arity incorrectly dispatched to the 3 argument get instead
of 2 argument get.
add :js to list of ops optimizable by and/or, add wrapping parens to
boolean exprs
add empty testing files
fix bug where nil could be a path in source map
source maps work with incremental compilation now
If output-to is :print if compiler redirects output. In that case set sourceMappingURL to source-map to avoid trying to open file :print.

Also update source map to use //# (new format) instead of //@ (old format).
make source map incremental compilation support even more
robust. previously source map support would not work for incremental
compilation across JVM runs. Now compiler tracks which files it has
seen, if a file has never been encountered and source maps are enabled,
then it will trigger a recompile, under :optimizations :none just checks
for existence of the corresponding .map file for each compiled .cljs
source file.

java.io.File -> File in compiler.clj

now that incremental compilation is more robust, remove reset hacks for
:optimize-constants and :advanced.
1934 -> 1978