Add support for boolean scalar data-type (Issue #9)

- support only for scalar booleans for the first. There will be an exception when trying to create boolean arrays
- Simplified setting values for bool registers - using `SetAtBit` and `GetBitAt` from snap7.
- In diagnostic tool display values for booleans as true or false but 0 and 1 also parsed to boolean from user

MR !20