Switch to autoconf to find libraries. Also, make a rudimentary make install command. We don't use anything fancy from autoconf yet (in particular, no config.h file), and we don't use automake or libtool. Most likely, this will happen later.
Stop linking unit tests et al against SDL_image and other things that only the demo program needs.
Split out some private utilities into effect_util.cpp, so we do not need to include e.g. Eigen from effect.h.
Add sdl-config --cflags and --libs when compiling.
Don't override GTEST_DIR if it already is set.
Link against -lpng, since we can now write screenshots in PNG format.
Add unit tests for GlowEffect.
Add an effect for padding.
Add the rest of the files for the premultiplied alpha commit.
When running make check, output which checks failed.
Added an overlay effect, implementing the atop effect.
Change to using GLEW everywhere. We could have done this on Windows only, but it's just as simple to keep the dependency list equal on all platforms. This subsumes our own extension-checking logic, too.
Use the -MP switch (make phony) for better dependency generation when files are removed.
Simplify the Makefile for building unit tests.
Only run the pkg-config line for Eigen3 once. Also, print an error message if pkg-config has failed.
Add an implementation of RPDF dither on the final output.
Make combine_two_pixels() handle the fact that the GPU has limited subpixel interpolation precision. Currently we only use it to somewhat improve the total_weight estimate to reduce the error slightly. However, the function can now also return the total error estimate, which will be useful for knowing when we can and cannot combine weights with reasonable error.
Add an effect for Lanczos resampling.
Add a unit test for YCbCrInput (not done yet).
Add a coverage target to the Makefile.