- Minor changes to cleanup some of the compiler warnings

* Added a bool to sbyte Utils convertor

As an attempt to avoid using any MarshalAs attribute for .Net Framework support this Utils method will take in a bool value and return a 1 for true or 0 for false sbyte.

* Changed all bool "MarshalAs" types to sbytes

Changed all previous BOOL types with "MarshalAs" attributes to SBYTEs and changed all the setters of them to use the Utils.BoolToSignedByte() convertor method.

* Fixed Utils bool convertor & added sbyte to bool

Improved the Utils bool convertor just casting an sbyte value to get rid of the unneeded sbyte array and added an sbyte to bool convertor to convert back the way to a C# bool assuming any positive value above 0 is a bool and no bools are packed in the single byte integer.

* bool to & from sbyte conversions via properties

All 1byte bools are now handled where they "sit", via public properties which perform the conversions to keep all external data able to communicate as it did before.

This change _only_ implements the low level API and makes no effort to update the LlamaSharp higher level abstraction.

It is built upon llama `b3f138d`, necessary DLLs are **not** included in this commit.