Add solutions for part 1

tools/builtInChips/Mux8Way16.hdl

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+// This file is part of www.nand2tetris.org
+// and the book "The Elements of Computing Systems"
+// by Nisan and Schocken, MIT Press.
+// File name: tools/builtIn/Mux8Way16.hdl
+
+/**
+ * 8-way 16-bit multiplexor.  
+ * out = a if sel == 000
+ *       b if sel == 001
+ *       etc.
+ *       h if sel == 111
+ */
+
+ 
+CHIP Mux8Way16 {
+
+    IN  a[16], b[16], c[16], d[16],
+        e[16], f[16], g[16], h[16],
+        sel[3];
+
+    OUT out[16];
+
+    BUILTIN Mux8Way16;
+}