RAxML-NG v0.4.1 BETA

Enhancements:

• better input validation and error reporting (alignment/starting tree)

Bugfixes:

• compilation with gcc7 (#17)
• failed assertion in MSA::remove_sites
• failed assertion in pllmod_algo_spr_round (fix libpll error propagation)
• fix excessive memory allocation during pattern compression (xflouris/libpll#143)