Merge pull request #40 from metakeule/master

add documentation with examples for jslib and link to it in the README
export build.Session
fixed parsing of command line options
added minification flag -m to build command, no actual minification yet
importing natives needs "js" arch
fixed testing multiple packages by removing Target and SourceMap fields from build.Options, since those were shared between Sessions and modified by build package code (breaks jslib)
removed jslib (i hope it will come back soon)
added build.ImportDependencies
detect global "self" object of web workers (fixes #41)
set "netgo" build flag to build "net" package without needing "C" (#43)
filter imports for ignored files
updated compatibility list (#43)
added syscall.setenv_c native
simplified method structure
fixed interface string bug
modified interface method data format
collect methods for anonymous fields of anonymous structs
replaced go$ and Go$ prefixes with just $ (fixes #42)
read natives for test packages
more tested packages