if telescope is started with an url while there is already another instance of it running and the -S flag is not provided, the link will be automagically opened into the running instance of telescope. Telescope now listens on a UNIX domain socket in ~/.telescope/ctl (or ~/.cache/telescope/ctl if XDG is used) for commands.

it's not spelled `util.h' because otherwise it'd get included instead of /usr/include/util.h

pagebundler is a helper that needs to be built with the *host* compiler because it's used to generate some sources. In normal situations, HOSTCC and HOSTCFLAGS are just ${CC} and ${CFLAGS}, but folks that cross-compile can specify there the host compiler and flags to successfully build telescope. The idea is largely based on what gforth does: it re-uses ${CFLAGS} for the host compiler though, while I'm adding an extra variable for that.