adding erase functionality; adding brush shape option on the brush settings canvas

README.md

@@ -29,17 +29,17 @@ Image menu
 - [x] Flip horizontal 
 
 Tools menu
-- [ ] Zoom (Zoom In, Zoom Out)
-- [ ] Erase
-- [ ] Color Picker
-- [ ] Paint brushes (with different textures/patterns)
-- [ ] Text box
+- [x] Zoom (Zoom In, Zoom Out)
+- [x] Erase
+- [x] Color Picker
+- [x] Paint brushes (with different textures/patterns)
+- [x] Text box
 
 Filters
-- [ ] Gaussian filter
-- [ ] Sobel filter
-- [ ] Binary filter
-- [ ] Histogram thresholding 
+- [x] Gaussian filter
+- [x] Sobel filter
+- [x] Binary filter
+- [x] Histogram thresholding 
 
 Shapes menu 
 - [ ] List of Shapes