Enable storing values of basic type

[ClemensLey]

When the evaluation of an expression does not change the state no transaction should be broadcast

[ClemensLey]

The Bitcoin Computer would only broadcast a transaction if the return type contained a value of object type. The reasoning was to prevent transactions from being broadcast when a getter is called.

However after some discussion we decided that there are use cases where it is an advantage to storing (potentially large) basic types or arrays of these. So we made the change that going forward the Bitcoin Computer will broadcast a transaction on any function call (or any expression evaluated). We note that reading will still be possible for free by using property accessors (for example a.n) for which no transactions are broadcast.