Define a dedicated `vmvar_t` type for values stored in variable pages
and propagate it through interfaces that expose those values. Keep the
type as int for now so this commit does not change runtime behavior.
This separates VM storage from ordinary int buffers and makes a later
conversion to 16-bit storage mechanically checkable.
This breaks save file compatibility for Daiakuji and Kaeru nyo Kuni nyo
Alice.
Due to an incorrect encryption code in ShArray.ChangeSecretArray, save
files were not interoperable with system3.9. (Even worse, this bug did
not affect the checksum calculation and did not cause a "corrupt save
file" error when a file saved with system3.9 was loaded with xsystem35
or vice versa.)
Fixes#41.
We only support a fixed set of modules, so dynamic linking isn't really
necessary. This paves the way for running System3.9 games on more
platforms.
NIGHTDLL is temporarily disabled, because many symbols conflict with the
SACT module.
kichikuou