Allow unencrypted connections

• Allow unencrypted database connections.
• Upgrade to C++20.

Bugfix and Linux release

• Allow compilation on Linux.
• Set up Travis CI builds for Linux and Windows.
• Use snapshot transaction isolation where available.
• Various bug fixes.

Auto-detecting SQL Server version

• Detect the best ODBC driver installed on the current computer.

SQL authentication

• Allow connections with username and password.
• Improve error messages.
• Log more in verbose mode.
• Output errors to stderr instead of stdout.
• Improve performance by writing to the console less frequently.

Standalone executable

Remove the dependency on the C runtime, only depending on Core Windows API.

First alpha

Initial release:

• only supports trusted authentication
• only supports SQL server
• only supports Windows
• basic substring search only