Theme system

Solves #1

Can choose between QtCreator's themes and base Vivy theme, or system's theme.

Depends on !21 (merged)

README.md

@@ -20,21 +20,14 @@ This project depends on cmake as a build system. For dependencies on
 Windows and MacOS, the easier thing to do is grab qtcreator and find a
 way to add the av libraries to it.
 
-#### Ubuntu/debian
-
-Vivy depends on Qt5 and libav. On ubuntu install the following packages:
-`qtbase5-dev qtchooser qt5-qmake qtbase5-dev-tools libavutil-dev
-libavcodec-dev libavformat-dev libmpv-dev cmake clang clang-format
-libomp-dev`.
-
-#### Arch/Manjaro
-
-TODO!
-
-#### FreeBSD and other toasters
-
-You will need cmake, qt and av dev packages. Set your favorite C++
-compiler with `-DCMAKE_CXX_COMPILER` and you're good to go.
+- Ubuntu/debian: Vivy depends on Qt5 and libav. On ubuntu install the
+  following packages: `qtbase5-dev qtchooser qt5-qmake qtbase5-dev-tools
+  libavutil-dev libavcodec-dev libavformat-dev libmpv-dev cmake clang
+  clang-format libomp-dev`.
+- Arch/Manjaro: TODO!
+- FreeBSD and other toasters: You will need cmake, qt and av dev
+  packages. Set your favorite C++ compiler with `-DCMAKE_CXX_COMPILER`
+  and you're good to go.
 
 ## Licence