Address lex.yy.c compiler warnings

[mabruzzo]

Pull request summary

I made 2 tweaks to the lexer code in order to address compiler warnings

Detailed Description

The specific changes include:

• I addressed the warning that the yyunput function is defined, but unused
  by adding the nounput option to parse.l
• I addressed compiler warnings about strncpy the case when we try to
  copy a line of text into our line buffer, but the line is larger than our
  line buffer.
  • I vaguely recall that there may be some safeguards in other areas of
    the code that should stop the program before we execute the code that
    the compiler was warning about.
  • But just in case we do encounter this scenario, I added logic to
    print out a warning to explain to users what is happening. Even if
    this code is never executed, it should make things a little more clear
    for future readers of parse.l.

Finally, I used flex to regenerate lex.yy.c from parse.l

[jobordner]

Looks good, free to merge.