Add top/bottom/left/right/width/height options

[RedSparr0w]

This PR adds top/bottom/left/right options which can be used instead of/with x/y.
I've also added width/height for images.

The readme/test have been added/updated, but I cannot run them on my computer.

closes #57

[ginkosen]

i need this feature!

[RedSparr0w]

@ginkosen You can use these features with this as your dependency:

  "dependencies": {
    "merge-images": "git+https://github.com/RedSparr0w/merge-images#develop-build",

[ginkosen]

@ginkosen You can use these features with this as your dependency:

  "dependencies": {
    "merge-images": "git+https://github.com/RedSparr0w/merge-images#develop-build",

Thanks. It's works for me .

Thanks again.

[ginkosen]

@ginkosen You can use these features with this as your dependency:

  "dependencies": {
    "merge-images": "git+https://github.com/RedSparr0w/merge-images#develop-build",

Thanks. It's works for me .

Thanks again.