Made TextColor independent of Stroke

[ashutoshshrm529]

A solution for #5

Here I have tried to make text color completely independent of stroke color.
I have also added another clone bitmap function ( text_bitmap ) which uses the text color instead of stroke. I preserved the original bitmap function since I was not sure about its uses elsewhere. Now the text color can be set using both the setTextColor function or the BeginText functions with color inputs.

Please review and suggest changes as you may see fit.

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[leonardocavagnis]

Since this library is based on the Processing API, and according to the Processing text() documentation, the font color should indeed be changed using the fill() function.

This PR is being closed due to inconsistency with the Processing API.