Beta version 1.6.beta

Notable new features:

• Polymorphism-aware models accounting for incomplete lineage sorting (code contributed by Dominik Schrempf).
• Lie Markov and non-reversible models (code contributed by Michael Woodhams).
• Heterotachy models accounting for rate variation across sites and lineages.
• Xeon Phi Knights Landing (AVX-512) support with 2X or more speedup.
• New option -fast to match the speed of FastTree program while still obtaining better trees [Experimental].

New features:

• -wql option now prints quartet area and corner in .quartetlh file (requested by Karen Meusemann).
• Support GENE resampling (-bspec GENE) and GENESITE resampling (-bspec GENESITE) for standard bootstrap with partition models.
• Sequential and multicore versions are merged, thus iqtree-omp executable becomes iqtree.

Bugfixes (inherited from 1.5.5-beta):

• Likelihood underflow for large multifurcating trees (e.g. consensus tree) (reported by Giap Nguyen).
• Crash with -minsupnew option (reported by Longzhi Tan).
• Compilation with gcc under Mac (thanks @ilovezfs).
• Crash with -nni1 for partition model -spp (reported by Diep).