Modify templates to accept compatible data types

Modify the templates to check if the receive data has a compatible
type with the target variable. Until this patch, only the same type was
accepted. Now, the code is able to make changes between data types.

Change-Id: I18d24cd9813601d10aa44982c3777e01649ee152
cmake: Fix error in CMakeLists.txt

Change-Id: I06c1392606200eca7bf165d19a5c1473baa9deb8
Prepare release 4.3.0

Change-Id: I0a53df4880a7f10d940154cd17b7cb191bbfd945
Prepare next development iteration

Change-Id: I8b2902ade13173a4bf476d9aed6594d3185a1a99
Add model for Mixer element

Change-Id: I87a2c13f0de599d37f7e5efc767e151664ed09ff
Change kurento logo

Change-Id: I61a5e023ddef361588644586b405d4da50462774