Added tracking of order by which tokens are processed by lexical analyser.
This helps in correctly formating error messages when constructs begin in one file, and end in another.
IEC 61131-3 Annex F Examples (informative)
This directory contains example code take from:
Annex F of Draft 2nd edition of the IEC 61131-3 standard (1998)
"PROGRAMMABLE CONTROLLERS - PROGRAMMING LANGUAGES"