Panic on well-defined but unsupported settings
Panic on well-defined but unsupported settings

When well-defined settings that are not supported by pq are
present in the environment, we currently ignore them. This
panics instead. Since unexpected values for settings like
PGTZ or PGCLIENTENCODING (which we do not actually support)
could cause data integrity issues, we should complain when
these are present.

bugreplaydev/pq,calebthompson/pq,stvp/pq,erichnascimento/pq,everalbum/pq,ympons/pq,johto/pq,springning/pq,dongzerun/pq,ympons/pq,flynn/pq,lib/pq,ScriptRock/pq,StabbyCutyou/pq,beni55/pq,cbandy/go-pq,jnewmano/pq,henrylee2cn/pq,amaniak/pq,bugreplaydev/pq,sammi/pq,VividCortex/pq,jnewmano/pq