Created read method on MString to read from sockets.

MString.cpp

@@ -6,6 +6,8 @@
 #include <format>
 #include <iomanip>
 #include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
 
 namespace coreutils {
    
@@ -247,6 +249,13 @@ namespace coreutils {
       }
       length = size;
    }
+
+   MString &MString::read(int fd) {
+      char ch;
+      while(::read(fd, &ch, 1))
+	write(ch);
+      return *this;
+   }
    
    int MString::offset() {
       return cursor - data;