formatter: parse name of built-in formatter templates in standard way
This slightly makes it easier to add "-Tjson(...)" handling, which should
be enabled only if the template specifier doesn't look like a literal
template. In other words, it should be handled after "if '{' in tmpl".
This makes "log -Tpickle" and "log -Tdebug" abort, which I think is better
than just printing "picklepicklepickle...".
max_width = 79
wrap_comments = true
error_on_line_overflow = true