add std::io::stream::ByteBuffer; fix std::io::Path::walk (#895)

* lib/std/io/stream: add some inlines

Signed-off-by: Pierre Curto <pierre.curto@gmail.com>

* lib/std/io/stream add ByteBuffer

Signed-off-by: Pierre Curto <pierre.curto@gmail.com>

* lib/std/io/path: fix free of paths in walk

Signed-off-by: Pierre Curto <pierre.curto@gmail.com>

* lib/std/bits: remove unnecessary receiver type

Signed-off-by: Pierre Curto <pierre.curto@gmail.com>

---------

Signed-off-by: Pierre Curto <pierre.curto@gmail.com>

test/unit/stdlib/io/bytebuffer.c3

@@ -0,0 +1,29 @@
+module bytebuffer_test @test;
+import std::io;
+
+fn void! write_read_test()
+{
+	ByteBuffer buffer;
+	buffer.init(0)!;
+
+	buffer.write("hello")!;
+
+	char[8] bytes;
+	usz n = buffer.read(bytes[..])!;
+	assert(n == 5);
+	assert((String)bytes[:n] == "hello");
+
+	buffer.write("hello world")!;
+	n = buffer.read(bytes[..])!;
+	assert(n == bytes.len);
+	assert((String)bytes[:n] == "hello wo");
+	assert(buffer.read_idx == 1);
+
+	char c = buffer.read_byte()!;
+	assert(c == 'r');
+	buffer.pushback_byte()!;
+
+	n = buffer.read(bytes[..])!;
+	assert((String)bytes[:n] == "rld");
+	assert(buffer.read_idx == 1);
+}