Release 2.03: Valgrind and MingW fixes

Bug fixing:

• Add SIGHUP handler to make valgrind happy when program closes (gets "hung up")
• Add -D_VALGRIND compile option to allow inclusion/exclusion of a few function calls to make Valgrind happy.

Release 2.02: fix compilation for MingW; added compilation instructions

• replace deprecated bzero() calls by memset calls
• added compilation instructions using mingw-gcc

Release 2.01: added man page, fix help messages

• Add man page
• Make help messages consistent between commandline (./connect --help) and man page

First release supporting HTTPS proxy servers

Initial release of reworked connect.c.
First release supporting HTTPS proxy servers.
The code has been reworked to compile cleanly using gcc-9 and -Wall -Wpedantic and is now also (mostly) 'valgrind-clean'.