shared_vector implementation

Shared ownership of a single C array.

Tracks offset and length for each instance
allowing each owner to "view" a different
piece of the array.

Parts of shared_vector<T> which can work
for T=void are in shared_vector_base<T>.
Specializations shared_vector<void>
and shared_vector<const void> handle
un-typed arrays.

Allow casting to/from typed vector

Offsets and sizes of untyped vectors are tracked in
bytes.  Therefore casting to types where sizeof(T)>1
is undefined if the offset is not a multiple of
sizeof(T).

pvDataApp/Makefile

@@ -26,6 +26,7 @@ INC += sharedPtr.h
 INC += localStaticLock.h
 INC += typeCast.h
 INC += printer.h
+INC += sharedVector.h
 
 LIBSRCS += byteBuffer.cpp
 LIBSRCS += bitSet.cpp