This began with a change to support "BRK <operand>" in cc65. The
assembler only supports this for 65816 projects, so we detect that
and enable it when available.
While fiddling with some test code an assertion fired. This
revealed a minor issue in the code analyzer: when overwriting inline
data with instructions, we weren't resetting the format descriptor.
The code that exercises it, which requires two-byte BRKs and an
inline BRK handler in an extension script, has been added to test
2022-extension-scripts.
The new regression test revealed a flaw in the 64tass code
generator's character encoding scanner that caused it to hang.
Fixed.