some std wrappers around libc

examples/tcp_server.zr

@@ -1,12 +1,12 @@
 func main[] : I64
     let s: I64 = net.listen(8000)
 
-    let resp: String = c.malloc(60000)
+    let resp: String = mem.alloc(60000)
     while true
-        let c: I64 = c.accept(s, 0, 0)
-        if c < 0
+        let conn: I64 = c.accept(s, 0, 0)
+        if conn < 0
             continue
 
-        let n: I64 = c.read(c, resp, 60000)
-        c.send(c, resp, n, 0)
-        c.close(c)
+        let n: I64 = c.read(conn, resp, 60000)
+        c.send(conn, resp, n, 0)
+        c.close(conn)