ext: dsent: adds a Python interface, drops C++ one

This patch extensively modifies DSENT so that it can be accessed using Python.
To access the Python interface, DSENT needs to compiled as a shared library.
For this purpose a CMakeLists.txt file has been added.  Some of the code that
is not required is being removed.

ext/dsent/tech/TechModel.h

@@ -1,3 +1,24 @@
+/* Copyright (c) 2012 Massachusetts Institute of Technology
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
 #ifndef __DSENT_TECH_TECH_MODEL_H__
 #define __DSENT_TECH_TECH_MODEL_H__
 
@@ -15,7 +36,7 @@ namespace DSENT
     using std::vector;
     using LibUtil::String;
 
-    class TechModel : public LibUtil::Config
+    class TechModel
     {
         public:
             typedef std::set<String>::const_iterator ConstWireLayerIterator;
@@ -25,6 +46,9 @@ namespace DSENT
             virtual ~TechModel();
 
         public:
+            // Get the value_ corresponding to the key_
+            const String& get(const String& key_) const;
+
             // Set the pointer to a standard cell library
             void setStdCellLib(const StdCellLib* std_cell_lib_);
             // Get the pointer to the standard cell library
@@ -64,8 +88,9 @@ namespace DSENT
             const StdCellLib* m_std_cell_lib_;
             // A set of available wire layers
             std::set<String>* m_available_wire_layers_;
+            // A map of model's parameters
+            std::map<String, String> params;
     }; // class TechModel
 } // namespace DSENT
 
 #endif // __DSENT_TECH_TECH_MODEL_H__
-