Merge pull request vslavik#47 from jbonigomes/markdownForReadme

Convert README to markdown

Author: vslavik

README

@@ -0,0 +1,130 @@
+## Usage
+
+diff-pdf is a tool for visually comparing two PDFs.
+
+It takes two PDF files as arguments. By default, its only output is its return
+code, which is 0 if there are no differences and 1 if the two PDFs differ. If
+given the `--output-diff` option, it produces a PDF file with visually
+highlighted differences:
+
+```
+$ diff-pdf --output-diff=diff.pdf a.pdf b.pdf
+```
+
+Another option is to compare the two files visually in a simple GUI, using
+the `--view` argument:
+
+```
+$ diff-pdf --view a.pdf b.pdf
+```
+
+This opens a window that lets you view the files' pages and zoom in on details.
+It is also possible to shift the two pages relatively to each other using
+Ctrl-arrows. This is useful for identifying translation-only differences.
+
+See the output of `$ diff-pdf --help` for complete list of options.
+
+
+## Obtaining the binaries
+
+Precompiled version of the tool for Windows is available from our
+[downloads](http://www.tt-solutions.com/downloads/diff-pdf-2012-02-28.zip)
+section -- the ZIP archive contains everything you need to run diff-pdf. It will
+work from any place you unpack it to.
+
+Precompiled version for openSUSE and Fedora can be downloaded from the
+[openSUSE build service](http://software.opensuse.org).
+
+
+## Compiling from sources
+
+The build system uses Automake and so a Unix or Unix-like environment (Cygwin
+or MSYS) is required. Compilation is done in the usual way:
+
+```
+$ ./bootstrap
+$ ./configure
+$ make
+$ make install
+```
+
+(Note that the first step, running the `./bootstrap` script, is only required
+when building sources checked from version control system, i.e. when `configure`
+and `Makefile.in` files are missing.)
+
+As for dependencies, diff-pdf requires the following libraries:
+
+- wxWidgets >= 3.0
+- Cairo >= 1.4
+- Poppler >= 0.10
+
+#### CentOS:
+
+```
+$ sudo yum groupinstall "Development Tools"
+$ sudo yum install wxGTK wxGTK-devel poppler-glib poppler-glib-devel
+```
+
+#### Ubuntu:
+
+```
+$ sudo apt-get install make automake g++
+$ sudo apt-get install libpoppler-glib-dev poppler-utils wxgtk3.0-dev
+```
+
+#### OSX:
+- Install Command Line Tools for Xcode `$ xcode-select --install` and
+[Homebrew](http://brew.sh) to manage dependencies, then:
+
+```
+$ brew install automake autoconf wxmac poppler cairo
+```
+
+Note that many more libraries are required on Windows, where none of the
+libraries Cairo and Poppler use are normally available. At the time of writing,
+transitive cover of the above dependencies included fontconfig, freetype, glib,
+libpng, pixman, gettext, libiconv, libjpeg and zlib.
+
+Precompiled version of the dependencies for Windows, built with MinGW, are
+available from our [downlods](http://github.com/vslavik/diff-pdf/downloads)
+section (wxWidgets is not included, as it supports MinGW well).
+
+
+### Compiling on Windows using MinGW
+
+1. First of all, you will need working MinGW installation with MSYS environment
+and C++ compiler. The instructions on installing MinGW can be found in the
+[MinGW website](http://www.mingw.org/wiki/Getting_Started):
+
+1. Once installed, launch the MinGW Shell tool. It will open a terminal window;
+type `$ cd /c/directory/with/diff-pdf` to do to the directory with diff-pdf
+sources.
+
+1. You will need to install additional MinGW components that are not normally
+included with MinGW, using these commands:
+
+    ```
+    $ mingw-get install msys-wget
+    $ mingw-get install msys-unzip
+    $ mingw-get install msys-perl
+    ```
+
+1. It's time to build the software now and give it some time to finish (Note
+that this step requires Internet connectivity, as it downloads some dependencies
+packages):
+
+    ```
+    $ make -f Makefile.mingw
+    ```
+
+1. If everything went well, diff-pdf is now in the `mingw\Products\`
+directory.
+
+
+## Installing
+
+On Unix, the usual `make install` is sufficient.
+
+On Windows, installation is not necessary, just copy the files somewhere. If
+you built it following the instructions above, all the necessary files will be
+in the `mingw\Products\` directory.