talkatu/talkatu

Added meson option to select if the demo application will be installed or not

2020-10-12, Sorvival
f744db8a2605
Added meson option to select if the demo application will be installed or not

Testing Done:
1. Compiled, installed with the default options and verified that the demo application and its manpage weren't installed.

2. Deleted `build` directory, reconfigured the install option added in this MR with `meson configure -Dinstall-demo=true` and then compiled and installed. This time the demo application and its manpage were installed in my system.

Bugs closed: TALKATU-84

Reviewed at https://reviews.imfreedom.org/r/156/
# Building
Talkatu uses [meson](https://mesonbuild.com) as it's build system.
Meson requires you to build in a directory other than the source directory.
To compile you can use the following commands:
```
meson build
cd build
ninja install
```