Report error messages for all unmatched templates.(2)

[sparverius]

See #1

Example to show desired output

#include "share/HATS/temptory_staload_bucs320.hats"
abstbox foo = ptr
implfun main0() = print$val<foo>(_)

Error message reported

Temptory/libats/DATS/print.dats: 60:1-14

60| fprint$val<a>(the_stdout<>(), x)
    ^^^^^^^^^^^^^ 
   error:  template instance not found: fprint$val<S2Ecst(foo)>

patsopt(CCOMP): there are [1] errors in total.
     exit(ATS): (1033)

[sparverius]

error message output via tacc

[githwxi]

I will take a look this weekend. Being involved with too much other stuff.