Proper README.

Author: neelance

README.md

@@ -1,32 +1,27 @@
-Successful Tests
-----------------
+GopherJS - A transpiler from Go to JavaScript
+=============================================
 
-- append.go
-- char_lit.go
-- complit.go
-- const.go
-- defer.go
-- empty.go
-- for.go
-- func.go
-- func6.go
-- func7.go
-- func8.go
-- initcomma.go
-- interface/bigdata.go
-- interface/convert.go
-- interface/embed.go
-- interface/fail.go
-- interface/noeq.go (with non-nil values)
-- interface/receiver.go
-- interface/struct.go
-- map.go (without float/nan tests)
-- recover.go
-- recover1.go
-- rename.go
-- simassign.go
-- solitaire.go
-- switch.go (without cases that only differ in type)
-- turing.go
-- typeswitch.go
-- varinit.go
+What is supported?
+------------------
+GopherJS is able to turn itself (and all packages it uses) into pure JavaScript code that runs in all major browsers. This suggests a quite good coverage of Go's specification. However, there are some known exceptions listed below and some unknown exceptions that I would love to hear about when you find some.
+
+Not yet supported
+-----------------
+Those features are not implemented yet, but on the roadmap:
+
+- implicit panics (division by zero, etc.)
+- exact runtime type assertions for compound types without a name
+- reflection
+- goroutines, channels, select
+- goto
+
+Derivations from Go specification
+---------------------------------
+Some tradeoffs have to be made in order to avoid huge performance impacts. Please get in contact if those are deal breakers for you.
+
+- int32, uint32, int64 and uint64 have emulated overflow, all other integer types do not
+- calls on nil cause a panic except for slice types
+
+Interface to external JavaScript
+--------------------------------
+A function's body can be written in JavaScript by putting the code in a string constant with the name `js_[function name]` for package functions and `js_[type name]_[method name]` for methods. In that case, GopherJS disregards the Go function body and instead generates `function(...) { [constant's value] }`. This allows functions to have a Go signature that the type checker can use while being able to call external JavaScript functions.