Log Message:
libansilove: update to 1.2.6.

libansilove 1.2.6 (2020-09-30)

- Introduce canvas' width/height variables and refactor canvas creation
- Refactor calls to drawchar() in the ANSI loader
- Refactor the ANSI loader to use a state machine
- Remove systematic filtering of Form Feed characters in Amiga mode
- Correct values for TUNDRA_COLOR_FOREGROUND and TUNDRA_COLOR_BACKGROUND
- Switch to using reallocarray(3) in the ANSI and PCBoard loaders
- Add a compat layer for systems which do not have reallocarray(3)
- Refactor canvas allocation for retina output
- Introduce the ANSILOVE_RANGE_ERROR macro, for values out of allowed range
- Error gracefully if canvas' width or height is equal to zero
- Remove an useless comparison in drawchar()
- Add some file format integrity checks in the Tundra loader
- Refactor error handling in several loaders