This introduces methods to increment and decrement the cursor position.
This is non-trivial as the cursor position is specified in bytes rather
than codepoints. Thus, it sometimes needs to be incremented or
decremented by more than one, depending on the codepoint to "jump over".
Because the cursor blink cycle needs to be reset after moving the
cursor, methods calling the ones in DOM::Position are implemented in
Frame. Furthermore, this allows the cursor_position() getter to stay
const. :^)
Additionally, it adds a offset_is_at_end_of_node() method which checks
if the current offset points to the end of the node.
SPDX License Identifiers are a more compact / standardized
way of representing file license information.
See: https://spdx.dev/resources/use/#identifiers
This was done with the `ambr` search and replace tool.
ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
