Minor updates to library to support msvc and XON/XOFF

[dontech]

Hello Andre,

Here is a small update to the library:

1. Support MSVC without warnings
2. Support XON/XOFF, as needed for 2 wire communication on some devices
3. Disable DTR by default, as some USB adapters set this, making libary unusable
4. Add missing PATH_MAX on MSVC
5. Dont use vasprintf, not available on all platforms

[dontech]

Please review and merge if applicable

[AndreRenaud]

Any chance you could sneak in the change to the non-windows code, with something like:

    // clear software flow control
    options.c_iflag &= (tcflag_t) ~(IXON | IXOFF | IXANY);
    if (HAS_OPTION('X'))
        options.c_iflag |= IXON | IXOFF;

[AndreRenaud]

Probably should be vsnprintf(buffer, sizeof(buffer)...?

[dontech]

Yeah, that would be more safe. I will fix this.

[AndreRenaud]

Thanks for submitting this. Looks reasonable enough.

[dontech]

Yeah sure, i will fix it up and resubmit

[dontech]

Any chance you could sneak in the change to the non-windows code, with something like:

    // clear software flow control
    options.c_iflag &= (tcflag_t) ~(IXON | IXOFF | IXANY);
    if (HAS_OPTION('X'))
        options.c_iflag |= IXON | IXOFF;

Yeah sure, i will fix it up

[dontech]

Hi Andre, i fixed up all the things you pointed out. Please review/merge

[AndreRenaud]

Thanks for this!