updated readmes and added linux build scripts

linux/BUILDING.md

@@ -0,0 +1,50 @@
+# Building and installing PaulXStretch on GNU/Linux
+Follow these steps in order to build (and install) PaulXStretch on GNU/Linux.
+
+### Installing build dependencies
+To build PaulXStretch you'll need to install the necessary development dependencies.
+
+If you're using Debian or a Debian-based distro like Ubuntu, run this script:
+```
+./deb_get_prereqs.sh
+```
+
+On Fedora run this script:
+```
+./fedora_get_prereqs.sh
+```
+
+On other distros you'll have to insall the following development packages manually through your package manager:
+* `libfftw3f-dev`
+* `libjack-jackd2-dev`
+* `libasound2-dev`
+* `libx11-dev`
+* `libxext-dev`
+* `libxinerama-dev`
+* `libxrandr-dev`
+* `libxcursor-dev`
+* `libgl-dev`
+* `libfreetype6-dev` or `libfreetype-dev`
+* `libcurl4-openssl-dev` or `libcurl4-gnutls-dev`
+
+### Building
+Run the build script, both the standalone application and the VST3 plugin will be built:
+```
+./build.sh
+```
+
+### Installing
+When the build finishes, the executable will be at
+`../build/PaulXStretch_artefacts/Release/paulxstretch`. You can install it
+and the VST3 plugins by running the install script:
+```
+sudo ./install.sh
+```
+It defaults to installing in /usr/local, but if you want to install it
+elsewhere, just specify the base directory as the first argument on the commandline of the script.
+
+### Uninstalling
+If you wish to uninstall you can run the uninstall script:
+```
+sudo ./uninstall.sh
+```