You need CMake, Vala 0.20 or later, libgee and gtk+. The repository includes a version of CMake for Vala that includes some changes (not mine) to support Valadoc. These changes still aren't available at the oficial repository. You can get the oficial files with
bzr checkout lp:~elementary-apps/+junk/cmake-modules
This will create a folder called cmake-modules. Inside it will be a folder called cmake. Copy the later to the Autovala project folder, overwriting the files inside.
Don't forget to keep the files FindValadoc.cmake and Valadoc.cmake, needed to work with Valadoc.
To compile and install it, just open a terminal, go to the directory where you downloaded the git repository and type:
mkdir install
cd install
cmake ..
make
sudo make install
sudo ldconfig
If you are using GTK 3.4 or previous, you must specify it to avoid the plugins to use newer widgets, not supported in old GTK versions:
mkdir install
cd install
cmake .. -DGTK_OLD=on
make
sudo make install
sudo ldconfig
Also, if you are using ElementaryOS Luna, the pandoc version available is also too old, so you must install the one from ubuntu 14.04 at least. The packages needed are pandoc, pandoc-data and libicu52, which can be downloaded from
http://packages.ubuntu.com
The Gedit and Scratch plugins are compiled and installed separately. Just follow the instructions available in each folder.