Detect file change

[YodaEmbedding]

qimgv seems to keep adjacent files in its buffer. (Probably to speed up switching back and forth between two images.) This is useful, except in one scenario: when an external program modifies an image.

Suggestions:

• When a file's datestamp changes, trigger its buffer as invalid.
• If a file's buffer is invalidated, reread the image from disk the next time the file is viewed.

[zwlshine]

@SicariusNoctis Hello， why I run ./build.sh in Ubuntu terminal, it has error in Makefiles fault

[easymodo]

@zwlshine you are probably missing some dependency

post the error here