The second argument of DC command specifies the maximum index of the new
array. That means, `DC _,n,_:` allocates an array of size n+1 (a[0] to
a[n]).
This patch makes sure various D commands work with a[n], and a[n] is
correctly saved and loaded.
Now loadSysVar() does not shrink array variables using the data count in
the save file, so that files saved by old xsystem35 binary can be safely
loaded. This also matches the behavior of System3.9.
kichikuou