Reads a String of at most i length

Property definitions

core $ Reader :: read
	# Reads a String of at most `i` length
	fun read(i: Int): String do
		assert i >= 0
		var cs = new CString(i)
		var rd = read_bytes_to_cstring(cs, i)
		if rd < 0 then return ""
		return codec.decode_string(cs, rd)
	end
lib/core/stream.nit:216,2--223,4