* PC_Sort and PC_IsSorted
* fixing -Wdeclaration-after-statement warnings
* using sort_r for a portable definition of qsort_r/qsort_s
* uncompression fallback for lazperf/is_sorted
* NEWS updated, sort_r github reference and README added
* Introduce LAZPERF_CPPFLAGS
Without this the las.hpp header file is not found when lazperf was
installed in a non-system place.
* Use GHT_CPPFLAGS
Without this the ght.h header file is not found when libght was installed in
a non-system place.
* Use tabs in Makefiles