Store unit map attributes as vmvar_t and derive VR/VW transfer sizes
from their element type. This prevents buffer overruns after vmvar_t
became uint16_t and fixes upward movement in Rance IV.
Add scenario coverage for both transfer directions and verify that
adjacent variables remain intact.
System 3.9 saturates compound addition and multiplication at 65535,
while an overflowing ascending loop stores the wrapped 16-bit result
after testing the wide value.
Update the scenario expectations and regenerated fixture to cover both
cases. The suite passes with xsystem35 and the original System39.exe.
Cover variable page allocation, array reference handling, and Shift-JIS
conversion in src_tests.
Extend the scenario suite with 16-bit boundary behavior for assignments,
loops, module results, and save/load round trips.
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