420034d5b5
Because cloning FGData from SourceForge using https does not work (this has been the case for *years*) whereas normal updates of an existing clone do work, and so does cloning the repository from its official GitLab mirror using https, this commits implements a special case in _gitDownload(): If the assembled clone URL is <https://git.code.sf.net/p/flightgear/fgdata>, then ask the user if he agrees to automatically clone FGData from GitLab and arrange the repository setup to fetch subsequent updates from SourceForge. This should be fine because <https://gitlab.com/flightgear/fgdata> is an official mirror of FGData. The default answer is thus to do so. It is automatically chosen when download_and_compile.sh is called with --non-interactive (new option). This implies that the initial use of download_and_compile.sh is again as easy as subsequent ones. This commits also adds the utility function _yes_no_quit_prompt() to repeatedly ask a question ($1) until a valid answer has been provided. The function automatically uses the default answer ($2) if --non-interactive has been passed to download_and_compile.sh. See the “discussion” at <https://sourceforge.net/p/flightgear/mailman/message/37017469/>.