Reduced code

* Procedure name is now shorter, easier to remember
* RGB component variables have shorter names, easier to use
* Final RGB color is already formatted for Praat, easier to use
* Hex -> decimal is now a single line, instead of a complex if-block.
* Conversion of hex pair components to decimal values is now a single line
* Reduced number of internal variables and length of names in general
* Converted initial hex string to lowercase, for easier manipulation
* Moved all color-procedures to the same file, so they can use each other.
* Separated tasks into three different procedures: `hex2rgb`, `rgb2praat`, and `hex2praat`
* Moved all color-procedures to the same file, so they can use each other.
* Separated tasks into three different procedures: `hex2rgb`, `rgb2praat`, and `hex2praat`