In a few places in src/wallet/wallet.h, we use a char when semantically we want a bool.

This is kind of an issue because it means we can unserialize the same transaction with different fFromMe flags (as differing chars) and evaluate the following section in wallet/wallet.cpp
```c++
        if (wtxIn.fFromMe && wtxIn.fFromMe != wtx.fFromMe)
         {
             wtx.fFromMe = wtxIn.fFromMe;
             fUpdated = true;
         }
```
incorrectly (triggering an fUpdated where both fFromMe values represent true, via different chars).

I don't think this is a vulnerability, but it's just a little messy and unsemantic, and could lead to issues with stored wtxIns not being findable in a map by their hash.

The serialize/unserialize code for bool internally uses a char, so it should be safe to make this substitution.

NOTE: Technically, this is a behavior change -- I haven't checked too closely that nowhere is depending on storing information in this char. Theoretically, this could break something because after this change a tx unserialized with such a char would preserve it's value, but now it is converted to a ~true~ canonical bool.

ninja check check-functional