Feat: Update primary color

[Biowulf21]

Hello @sadespresso, I have refactored my code to implement #105. Please do check it out.

I have found a small quirk with regards to keeping the primary color on the local storage though. Android seems to backup local storage - and by extension, the primary color - for devices with android API >= 23 even after uninstalls. There is a way to clear them by editing the AndroidManifest.xml file.

Let me know what your preference is with regards to this.

Thanks!

[sadespresso]

So there are several problems we have now:

• The bottom navigation color is somehow inverted
• As you can see in the picture below, the primary color does not have enough contrast with the background
• Secondary color is not same hue as the primary color
• The default primary color is not Flow's brand color
• It's not really good idea to specify colors in each widgets when we can set it on the theme.

I think it's better to dynamically generate the color scheme, and reconstruct the theme from it.

I also think there are so many things need to be reconsidered before making any more progress.

Again, thank you for the implementation ^^