Hi,
I think that two version of vala installed on the same machine aren't
a good idea,
so if you have not done yet please remove the ppa version.
To make the configure test pass you should include your $HOME/lib/pkg-
config directory
on the list of directory searched by pkg-config. You can do this by
adding it to the PKG_CONFIG_PATH:
export PKG_CONFIG_PATH=$HOME/lib/pkg-config
I'm not sure about the directory, but is the directory where you find
vala-0.10.pc file see man pkg-config for futher details.
Also, to compile vtg, you have to add to the configure script the path
where the vapi files can be found:
./configure --with-valavapi=$HOME/share/vala-0.10/vapi
I hope this helps,
Andrea