Release v2.23.0

• Added possibility to format a result as a fraction.
• Added direct and inverse fast Fourier transform: new functions fft abd ifft.
• Added a new context menu button that switches the insertion mode: before or after the selected term.
• Fixed a bug: an operation with an array on the top of equation results NaN or an invalid value.
• Fixed a bug: 3D plot fails whenever one interval is used twice.
• Fixed a bug on Android 12: soft keyboard disappears when a formula is expanded.

See https://github.com/mkulesh/microMathematics/projects/7 for more details