Move generatePrologBasics into Makefile

The motivation for this change is twofold:

• First, we get a cleaner separation of concerns, since sicstusbasics.pl no longer contains shell commands that describe how to copy itself around, instead the Makefile deals with this.
• Secondly, under MinGW on Windows make (including recursive invocations) has access to Unix tools like sed or cat, but subprocess calls from sicstus do not (since sicstus uses the native Microsoft VC runtime rather than a Unix emulation). This resulted in errors when trying to call these tools from generatePrologBasics, which we sidestep by moving the logic into the Makefile directly.