It is no longer a disabler, so passing it to required: does not turn off that
dependency like it should. Also, the options in the projects were renamed.
Testing Done:
`meson configure -Dintrospection=false`, plus a bunch of plugin options off too since that need introspection.
Reviewed at https://reviews.imfreedom.org/r/266/
# UPDATING VERSION NUMBERS FOR RELEASES
#
# The version number is:
# <major>.<minor>.<micro><extra>
#
# micro += 1
#
# If any functions have been added to libpurple, Pidgin, or Finch:
# micro = 0
# minor += 1
#
# If backwards compatibility has been broken in libpurple, Pidgin, or Finch:
# micro = 0
# minor = 0
# major += 1
# purple_soversion += 1
#
# extra should be similar to one of the following: