Fix repeat of 0, O commands with larger integer values

[dymk]

Two bugs that this fixes -

1. o100 repeat [0] would fail. I think this was due to skipping being true by the time the parser got to the matching endrepeat, so it would effectively just end up skipping to the end of the file. The fix is to not check if we're skipping when we encounter an endrepeat I think, because we already check if the top of the stack is its matching repeat label.
2. o300 if [1] would fail because the int value of 300 is cast to an int8_t, which is too small a type to contain 300. Upgraded int_value to int32_t to avoid this.

repeat tested with the following

--- (gcode ----
(print, start)
o100 repeat [0]
(print, fail repeat 0)
o100 endrepeat

#<count> = 0
o200 repeat [3]
#<count> = [#<count> + 1]
o200 endrepeat
(print, pass, count=%d#<count>)

o300 if [#<count> EQ 3]
(print, pass if)
o300 else
(print, fail if)
o300 endif

--- (output) ----
$LocalFS/Run=repeat.nc
ok
[MSG:INFO: PRINT, start]
[MSG:INFO: PRINT, pass, count=3]
[MSG:INFO: PRINT, pass if]