Improvements and changes

[vlad-roid]

Differences in this branch from original repository

• Added a "no color" option (transparent color value)
• Original bitmap generation was prone to crashes, which are instead caught in this fork's source code
• Original HuePicker, OpacityPicker and SatValPicker have memory leaks, which are fixed in this fork's code
• For the above changes, HuePicker provides the method setBitmapGenerationFailedListener which listens for bitmap generation failure; ColorPickerDialog uses this listener to automatically reattempt reloading the bitmap every second while the dialog is still showing
• Migrated from legacy support library to AndroidX AppCompat v1.1.0, leaving inflation of the correct Button classes to the implementations of this library

Other internal changes:

• Library updates: Gradle wrapper 3.3 -> 5.4.1; Gradle build tools 2.2.0 -> 3.5.1; Maven gradle plugin 1.5 -> 2.0; Compile/Target Android SDK level 25 -> 29; Min Android SDK level 11 -> 14; Android build tools 23.0.3 -> 29.0.2
• Switched from deprecated compile to api in build.gradle
• Fixed spelling mistake "dialog_edit_color_root.xml"
• Removed application declaration from manifest to prevent transitive changes
• Added missing items to .gitignore
• Standard Android Studio source code formatting
• Minor refactoring inside onInterceptTouchEvent of ScrollViews
• Removed redundant minSizePx variable from HuePicker and OpacityPicker