feat: Customisable WaveHz

[Kalaiz]

• Users can change wave speed manually; Any value [0,1]. This will give them more control on the speed of the wave. Example of using custom hz value for wave:

Users simply have to set the newly altered attribute wave_hz:

wave:wave_hz="0.09"
wave:fill_to_brim="true" />

• Upgraded Gradle plugin version to 4.11 and Gradle version to 6.5 While running on Android Studio IDE 4.1.1,a prompt to upgrade Gradle appeared"Support for builds using Gradle versions older than 2.6 was removed in tooling API version 5.0. You are currently using Gradle version 2.2. You should upgrade your Gradle build to use Gradle 2.6 or later."

• Updated and fixed minor issue regarding badge in README:

• Added public getter for progess (#21)