FMSLogo Code

Fix copy&paste error in MCI MIDI example: "video" -> "music"

Replace filenames of "dummy.fil" with "example.txt" in examples.
This improves the readability of the examples.

Refactoring: Extract sendvalue_helper() to remove duplicated logic.

Add logic to enforce that the commander's read/write posistion is -1.

Before, this behavior, although documented, depended on undefined behavior from stdlib. A recent change silently altered this behavior, allowing setting and getting the posistion of the commander's write stream. This revision adds logic to FMSLogo to explicitly provide the documented behavior. It also adds regression tests and clarifies the documentation.

If I had created READPOS/SETREADPOS/WRITEPOS/SETWRITEPOS today, it would be an error to apply them to the commander. However, for backward compatibility with old programs, I retained the behavior of outputting -1 when getting the position and doing nothing when setting it.

Add missing #include to fix a build break when compiling w/o precompiled headers

Fix the File API's special "clipboard" file to correctly handle Unicode.
It now writes a BOM and encodes the fake file in UTF-8.

Fix a bug that corrupted some three-byte UTF-8 character encodings

Merge in changes to clipboard handling from trunk.

Merge in changes to clipboard handling code from trunk.
The merged logic is not correct for Unicode, because it doesn't insert a BOM to the beginning of the clipboard file.
This will be fixed in a subsequent commit.

Replace win32-specific clipboard code in the File API with platform-independent code.
This brings FMSLogo one step closer to running on GNU/Linux.
It also fixes a bug where a NUL character was written to the end of the clipboard file.