The following changes have been applied to src and lib folders:
regex replace: ([^"_])NULL ⇒ \1nullptr (8968 chgs in src, 1153 in lib)
Manually find/change: (void \*) nullptr ⇒ nullptr (1 case)
regex find: ".*?nullptr.*?"
Manually ~14 cases back to "NULL" in src, ~2 in lib
regex finds a few false positive where nullptr appears between two
strings in a function call
EAM styles have a single function but are not compatible, so we test for
single_enable == 0 and manybody_flag != 0.
Improve explanation in the documentation about which pair styles are not supported.
