Added a function to convert frequencies from one to another unit.

There are new conversion units added to convert Frequencies (visable in the keyboard mode).

You can now convert every unit between:
- Hertz
- Kilohertz
- Megahertz
- Gigahertz
- Terahertz
Status Job ID Name Coverage
  Build
passed #1118114
build:fedora

00:04:26

passed #1118115
build:ubuntu

00:02:53

 
  Test
passed #1118117
test:fedora

00:03:48

passed #1118116
test:ubuntu

00:02:54