Start documenting libraries dependencies and how to configure them

Former-commit-id: 21620a3f08de0f2e1cfd759802a2b367bbe83f6b

INSTALL.swift

@@ -58,10 +58,35 @@ for instance. GCC address sanitizer flags can be included using the
 
 option. Note this requires a GCC compiler version of at least 4.8.
 
-Dependencies: needs to be filled in...
+SWIFT currently requires a compiler with OpenMP support.
 
 
-    
+                                 Dependencies
+                                 ============
 
+SWIFT depends on a number of thirdparty libraries that should be available
+before you can build it.
 
 
+HDF5: a HDF5 library is required to read and write particle data. One of the
+commands "h5cc" or "h5pcc" should be available. If "h5pcc" is located them a
+parallel HDF5 built for the version of MPI located should be provided. If
+the command is not available then it can be located using the "--with-hfd5"
+configure option. The value should be the full path to the "h5cc" or "h5pcc"
+commands.
+
+
+MPI: an optional MPI library that fully supports MPI_THREAD_MULTIPLE.  
+Before running configure the "mpirun" command should be available in the
+shell.
+
+
+METIS: a build of the METIS library can be optionally used to optimize the
+load between MPI nodes (requires an MPI library). This should be found in the
+standard installation directories, or pointed at using the "--with-metis"
+configuration option.  In this case the top-level installation directory of
+the METIS build should be given. Note to use METIS you should at least supply
+"--with-metis".
+
+
+DOXYGEN: the doxygen library is required to create the SWIFT API documentation.