Fix Panic in Go 1.6

In windows cannot "go get ...",for  "undefined reference to libiconv"

please  patch it so as to support more os

* moved sample programs to examples directory
 * cleaned up make make file
 * converter.go: ConvertString now uses Convert under the hood, removes some code duplication
 * reader.go: No need to have two separate buffers, can write directly in to buffer given in Read call. Simplifies code greatly

* string conversion
 * byte slice conversion
 * Reader conversion