cosmetics, separate yuck commands by form feed \f
minor, hand over value of configure M4 to config.h (as YUCK_M4)
minor, provide yuck config subcommand
minor, employ semantics for global option -o|--output in cmd_config()
chore, replace PKG_CHECK_EXISTS and _PKG_CONFIG macro calls with `yuck config'
minor, only use system-wide yuck when --with-included-yuck is not yes
chore, kick duplicate message `checking for yuck'
chore, kick yuck.pc.in and yuck.pc generation
Merge branch 'feat/kick-pkg-config-dep'

* feat/kick-pkg-config-dep:
  chore, kick yuck.pc.in and yuck.pc generation
  chore, kick duplicate message `checking for yuck'
  minor, only use system-wide yuck when --with-included-yuck is not yes
  chore, replace PKG_CHECK_EXISTS and _PKG_CONFIG macro calls with `yuck config'
  minor, employ semantics for global option -o|--output in cmd_config()
  minor, provide yuck config subcommand
  minor, hand over value of configure M4 to config.h (as YUCK_M4)
  cosmetics, separate yuck commands by form feed \f