Autotools-based builds will be supported for some time. This patch makes
some modifications to the Autotools build system necessary to to co-exist
with meson.
- LOCALEDIR and DATADIR won't be defined, replace with GEANY_* where necessary
- VERSION won't be defined, use PACKAGE_VERSION and PACKAGE_STRING instead
- Doxyfile cannot be generated by configure, which wouldn't run in a meson
build. Generate both Doxyfile and Doxyfile-gi manually using sed
- actual shell script to generate signallist.i (inline shell not a thing in meson)
- path of signallist.i will change, exclude callbacks.c from doxygen
to make it happy
- geany icon for 24x24 size such that one exists for all sizes
- install license file for Lexilla
- change how tests are run a bit so that runner.sh will also work for meson
- check for dirent.h, required by ctags