Fix SubString{UTF8}

* case which led to endof < 0
* out-of-bounds case
Fix replace for UTF8 strings
Fix redirection deprecation warnings
Use `|>` for function piping instead of `|`
fix trivial README confusion
Merge branch 'master' of github.com:JuliaLang/julia
syntax error for non-unique arguments and/or static parameters
fixes #3432
Merge pull request #3433 from danluu/gcc_xor_clang

Clarify compiler depdencies
Merge branch 'master' of github.com:JuliaLang/julia