Added md5 checksum for binary file

st-flash: minor usage fix, and make cmdline parsing more user friendly

Somewhat fix the help message that showed some parameters as mandatory,
when in reality they depend on the operation type and file format.

Try to show explicit error messages for the most common mistakes.

- Updated travis CI build configuration
- Updated project references
- Minor formatting fixes

Enhanced error log with file path for map_file()

Fixed broken build on 32-bit systems

Fixed st-flash write 0xff ignored issue

- Updated CHANGELOG.md
- README.md: Edited note on licensing.
- Formatting in tutorial.md

Temporarily removed travis-lin-mingw script for clean travis builds.

Fixed st-info --probe mechanism

serial match was not done for v1 device, resulting in attempting to open it systematically,
leading to some libusb device claim call failure.
Lookup device serial for all chips, compare it if needed, and continue.

we return count and list of successfully probed devices, no need to free
everything if some libusb call of the last probe attempt failed.

actually open all counted devices - the two vid check need to be aligned.
also now display if some st device has been skipped.

ease v1/v2/v2.1/v3 identification and supported devices filtering

- Whitespace fixes
- Removed old appveyor-mingw script
- travis-lin-mingw.sh -> .gitignore

Fix dead loop after an unexpected unplug

ext_pkg_versions

-> error: ‘O_BINARY’ undeclared
-> tabspaces in Makefile

-> error: ‘O_BINARY’ undeclared
-> tabspaces in Makefile

* Fix by adding error handler in gdb-server
* Enhance logs for functions with return values

Legacy issues

(Fixes #788)