cant set byte datarefs

[SamuelReithmeir]

as discussed in issue #38 we cant set string/byte datarefs. there exists a branch "feature/setting_byte_array_datarefs" on which there is a (not entirely functioning) fix for this problem. It won't compile because "m_value" is sometimes referenced as "_value" and "m_newValue" as "_newValue". After adding the necessary "m"s it compiles just fine and i can set string datarefs more or less, e.g it doesn't write the \0 character so if i write "123" to a dataref which contained "foobar" it will now contain "123bar".