C API ninjaCom refactor and implementation

[masonwillman]

In #582, we decided to refactor ninjaCom for API functionality. Please reference this comment for the description of the new ninjaCom design.

Examples of different ways a user could specify their FILE* stream via the API:

// Multiple specified streams
FILE* progressStream;
FILE* errorStream:
char** options;
int NinjaErr = NinjaSetProgressStream(FILE* progressStream, options); // if FILE* = NULL, assume stdout
int NinjaErr = NinjaSetErrorStream(FILE* errorStream, options); // if FILE* = NULL, assume stderr

// 1 unified stream
FILE* stream;
char** options;
int NinjaErr = NinjaSetStream(FILE* stream, options);

// 1 stream with custom messages
bool msgType1, msgType2, ...;
FILE* stream;
char** options
int NinjaErr = NinjaSetCustomStream(FILE* stream, msgType1, msgType2, ..., options);

Once set, it is on the user to use the messages provided by the stream, like outputting them in their application or error logging.

[masonwillman]

To implement this on the GUI, I would look into QSocketNotifer. Based on the documentation here, this should be able to work with file descriptors, like a FILE*. Specifically, it says "QSocketNotifier makes it possible to integrate Qt's event loop with other event loops based on file descriptors." I would review this and see about integrating it once the functionality is exposed in the API.