updated INSTALL to conform with autotools

added a short HACKING introduction

HACKING

@@ -0,0 +1,35 @@
+                 -------------------------
+                  strongSwan - Development
+                 -------------------------
+
+For interested developers, we have a public repository. To check out and 
+compile the code, you need the following tools:
+
+    - Subversion (1.3.1)
+    - a recent GNU C complier (gcc-3.4.6)
+    - recent autotools (autoconf-2.59, automake-1.9.6, libtool-1.5.22)
+    - the usual strongSwan dependencies (gmp >= 4.1.4, optional curl, ldap)
+    - perl (5.8.8)
+    - lex (flex-2.5.33)
+    - yacc (bison-2.1)
+    - gperf (3.0.1)
+    - Doxygen (1.4.6)
+
+The numbers in brackets represent the versions used on our development systems,
+other version MAY work, too. Not all tools are checked by the configure script,
+as they are not needed in the tarball distributions, so check them manually.
+
+To check out the trunk, use:
+
+    svn co http://www.strongswan.org/ikev2/trunk strongswan
+
+After a successful check out, give the autotools a try:
+
+    cd strongswan/
+    ./autogen.sh
+
+Then you're in, start the build as usual:
+
+    ./configure [options]
+    make
+    make install