Add horizontal adjustment to chroma decoder / gen_chroma scripts

[harrypm]

Currently, the commands available only allow for vertical video area adjustment image output-wise, as --full-frame is broken.

However, this does not cover 100% of active picture output in some cases and can be left or right-side biased so having these 2 commands implemented would be ideal.

--horizontal_positon_left --hpl

--horizontal_positon_right --hpr

The pixel range would be 0-16 left & 0-12 right.

Description: Adjusts the horizontal plane of rendered video area, which is useful if the tape image signal is not centred.

Full-Frame Example

Ideal VBI Area Example

[harrypm]

Technically solved in pull #152 needs some improvemnet as there is no boundry limits and can crash ld-analyse and generate way too shifted output on the chroma-decoder rendered video file.