Address build warnings (#3082)

* do not throw in desctructor

* remove unused var; reserve

* provide operator= for DiscreteValueVect

* provide operator= for SparseIntVect

* remove unknown 'omp' #pragmas; refactor loop

* remove unused var

* remove unused variables

* give EmbeddedAtom a default constructor & early exit on self assignç

* handle unused vars/args

* catch exception by ref

* address unused args

* fix signed type comparison; refactor extra checks

* remove unused variable

* suppress switch fallthtough warning

* handle signed type comparison

* handle signed type comparison

* potentially uninitialized vars

* fix abs() of bool

* unused vars in catch statements

* remove unused variables

* python::list returns will be copied

* give ValidationMethod constructor & virtual destructor

* remove extra semicolon

Code/DataStructs/SparseIntVect.h

@@ -49,6 +49,15 @@ class SparseIntVect {
     initFromText(pkl, len);
   };
 
+  SparseIntVect &operator=(const SparseIntVect<IndexType> &other) {
+    if (this == &other) {
+      return *this;
+    }
+    d_length = other.d_length;
+    d_data.insert(other.d_data.begin(), other.d_data.end());
+    return *this;
+  }
+
   //! destructor (doesn't need to do anything)
   ~SparseIntVect() {}