The DTLS transport layer implementation with 'tinydtls' is now
encapsulated into an object library in the CMake project. This makes the
project more modular.
This code is part of Wakaama and should therefore be prefixed with
`lwm2m`. The code can optionaly be use in another project that leverages
Wakaama code. Therefore all Wakaama code has to be prefixed to reduces
the posibility of naming clashes. Moreover it improves readability of
the code.
