Improve the INSTALL file.

git-svn-id: svn+ssh://svn.berlios.de/svnroot/repos/libssh/trunk@750 7dcaeef0-15fb-0310-b436-a5af3365683c

INSTALL

@@ -9,7 +9,10 @@ In order to build libssh, you need to install several components:
 - A C compiler
 - [CMake](http://www.cmake.org) >= 2.6.0.
 - [openssl](http://www.openssl.org) >= 0.9.8
+or
 - [gcrypt](http://www.gnu.org/directory/Security/libgcrypt.html) >= 1.4
+
+optional:
 - [libz](http://www.zlib.net) >= 1.2
 
 Note that these version numbers are version we know works correctly. If you
@@ -22,15 +25,17 @@ First, you need to configure the compilation, using CMake. Go inside the
 
 GNU/Linux and MacOS X:
 
-    cmake -DCMAKE_BUILD_TYPE=Debug ..
+    cmake -DCMAKE_INSTALL_PREFIX=/usr -DCMAKE_BUILD_TYPE=Debug ..
     make
 
 ### CMake standard options
-Here is a list of the most interesting options provided out of the box by CMake.
+Here is a list of the most interesting options provided out of the box by
+CMake.
 
-- CMAKE_BUILD_TYPE: The type of build (can be Debug Release MinSizeRel RelWithDebInfo)
-- CMAKE_INSTALL_PREFIX: The prefix to use when running make install (Default to
-  /usr/local on GNU/Linux and MacOS X)
+- CMAKE_BUILD_TYPE:     The type of build (can be Debug Release MinSizeRel
+                        RelWithDebInfo)
+- CMAKE_INSTALL_PREFIX: The prefix to use when running make install (Default
+                        to /usr/local on GNU/Linux and MacOS X)
 - CMAKE_C_COMPILER:     The path to the C compiler
 - CMAKE_CXX_COMPILER:   The path to the C++ compiler
 
@@ -42,12 +47,13 @@ Options are defined in the following files:
 
 They can be changed with the -D option:
 
-`cmake -DCMAKE_BUILD_TYPE=Debug -DWITH_LIBZ=OFF ..`
+`cmake -DCMAKE_INSTALL_PREFIX=/usr -DCMAKE_BUILD_TYPE=Debug -DWITH_LIBZ=OFF ..`
 
 ### Browsing/editing CMake options
 
 In addition to passing options on the command line, you can browse and edit
-CMake options using `cmakesetup` (Windows) or `ccmake` (GNU/Linux and MacOS X).
+CMake options using `cmakesetup` (Windows), `cmake-gui` or `ccmake` (GNU/Linux
+and MacOS X).
 
 - Go to the build dir
 - On Windows: run `cmakesetup`