Fix scrolling jump between pages

[sergiogarciadev]

This PR fixes #5.

To effectively fix this, we need to have in memory the previous and next caches (4096 bytes), which means that instead of loading just 4096 bytes we must load 3x that, this has no significant impact on performance due to still being very small.

It may have a small performance impact on search, due to repeated reading the same blocks, but due to OS cache this should be minimal and it avoid a major refactor on project.

[merces]

Wow, thanks for working on this. I tested it and it indeed solves this problem, but it somehow breaks long searches.

To reproduce:

1. Unpack putty.exe from putty.zip
2. Open putty.exe in dz6.
3. Press /, type tamperproof, then Enter.

It goes to F33A8, but the string is actually at F23A8.

It also breaks o key if the next other byte is far from the current offset:

1. Unpack ls from ls.zip.
2. Open ls in dz6.
3. Go to offset 0x30 with :30.
4. Press o.

It goes to 0x1000, but the next other byte is at 0x4000.

Also Alt+s shows 2604 strings in ls, which is exactly three times 868 (the correct number of strings).

Do you think you can fix it?

Thanks in advance.

[sergiogarciadev]

This was supersede by #24