Build/upload goserver too

Count our line-offsets only AFTER we've updated IFs.

Nowadays we rewrite some IF statements, turning this:

        IF A < B THEN 300 ELSE 400

into this:

        IF A < B THEN GOTO 300 ELSE 400

By doing this we change the length of our program, and that means
that any calculated line-number -> program-offset mapping is
off.  Calculate the line-number indexes _after_ expansion, to
ensure they're always correct.

Merge pull request skx#83 from skx/allow-raw-line-for-if

Allow omitting GOTO for IF-tests.

Avoid negative indexes on array-accesses.

Found via fuzzing :)

Minor improvement in test-coverage

More godoc improvements for skx#72

More bounds-checking on parsing of DEF FN.

This closes skx#67.

Removed ineffective assignment

Allow digits in variable-names.

This was a simple change, as we only start searching for identifiers
when we hit a non-digit.  This means if we remove the restriction
on numbers we're already guaranteed that we'll have things that
don't have a leading digit.

Added test case for same.

This closes skx#62.

Increased test-coverage