Enhance image type support (#18)

* adds tiff support

* doc update

* adds memory-based =IPixelariumImage= implementation

* add usage example for custom user control

* enhance

* clang-format

fix readme

fix docs

Readme.org

@@ -17,6 +17,17 @@ It tries to be as flexible as possible.
 
 This is still work in progress and will change significantly.
 
+* Supported Types
+
+Currently, Pixelarium supports the following image file formats:
+- jpeg
+- png
+- tiff
+- czi
+
+
+where possible, the [[https://docs.opencv.org/3.4/d4/da8/group__imgcodecs.html][OpenCV codecs]] are used to interpret the respective file type. The czi-format is supported via [[https://github.com/ZEISS/libczi][libCZI]].
+
 * Prerequisites
 
 Dependencies are either submodules in the =modules= subdirectory or artifacts of the cmake build process from the =cmake= directory. This repository should therefore be cloned recursively:
@@ -88,3 +99,7 @@ This is the most straight-forward usage of Pixelarium. It simply instantiates a
 ** [[file:examples/custom_0/][custom_0]]
 
 This is meant to showcase that [[file:lib/app/DefaultApp.hpp][=DefaultApp=]] ([[file:lib/app/AppGLFW.hpp][=AppGLFW=]] as well) is meant to be customized via inheritance.
+
+** [[file:examples/custom_1/][custom_1]]
+
+Is a slightly more involved example showcasing how to inject a user defined control into the existing scaffolding of =DefaultApp= using a multiplication filter.