Notes:
1) arguments of realpath() and _fullpath() are in reverse order
2) 2 calls of strchr() are needed because / and \ are valid path separators on Windows
If lottie contents were designed in white color, gif result is invisible.
we can generate gif with a specified bg color.
lottie2gif [lottieFileName]
lottie2gif [lottieFileName] [bgColor]
example:
lottie2gif sample.json //white bg color in default.
lottie2gif sample.json ff0000 //red bg color
