Set minimum required to 3.4 across the board. Use standard
GNUInstallDirs variables instead of custom INSTALL_BIN_DIR and
INSTALL_LIB_DIR. Use generator expressions and commands instead of
variables when possible. Use Runtime, Development, and Libraries
components in the installation. Set up the layout of the build tree
to match the installation tree. Replace compiler-specific flags with
more general cross-platform settings when possible. Update COMPILE
with new configure and install instructions. Add alias targets.