20191025

• Upgrade CPython to 3.7.5
• Upgrade pip and setuptools to latest versions
• Upgrade SQLite to 3.30.1
• Upgrade OpenSSL to 1.1.1d
• Upgrade libressl to 3.0.2
• Fixed read-only files in archive
• Enable building on Catalina. This required unshipping our own Tcl/Tk libraries as well as the Tix library. The tkinter extension module now depends on the system Tcl/Tk frameworks, which should always be available (but are deprecated).