* this function essentially provides the same functionality as FunctionTransform with the addition of directly committing the result to the filesystem
** this is needed if one wants to generate doctype-containing transformations from inside a transformation as "write-file" is not able to infer the doctype of a given xalan::XalanNode pointer
** this is a integral limitation of (at least) XSLT 1.0 as implemented in Apache Xalan
*** a document can of course only have a single document type
*** e.g. we can not include a doctype node in the result tree of FunctionTransform
* implemented test case for FunctionGenerate
* transformation "test.xsl" is shared between the FunctionTransform and FunctionGenerate test cases
* modified README.md accordingly

* neither the constructor nor the generate member methods need to be templatized
** only supported "output" argument is now a reference to a "std::basic_ostream<char>" instance
** the caller is responsible for e.g. writing the output to disk
* this was done to simplify the basic interface of InputXSLT
* removed "default_params" testcase along with default parameter generation
** this feature is neither used nor required

* slightly improved FunctionTransform test case utility templates

* variables containing the output of a external function can be defined using the "select" attribute
** tree-like definition is only needed when helper templates such as "transformer" are used
** queries on variables that are instantiated in this fashion need the "self::" prefix before base nodes
* changed includes of the "testcase.xsl" base template to imports
** this signifies that the importing template is based on the imported template
** ... and this is exactly what we want to define

* the root node of the result tree of each function is a domain element
** i.e. the root node of "read-xml-file" is "file", the root node of "read-directory" is "directory"
* the root node contains the result state of the function call encoded in a "result" attribute
** possible values are "success" and "error"
** the root node may contain additional attributes such as the target path of a called transformation
* the actual function result is contained within the child nodes of the function root node
** i.e. the XML file tree returned by "read-xml-file" is a child of the function root node
** if specific errors occured they are also returned as child nodes of the function root node
*** this is currently only the case for "transform" where transformation errors are returned as "error" value node childs of the function root node
* updated test cases accordingly

* verifying type attribute and extension value node if available

* test case requires markdown.pl formatter to be available in "/usr/bin/"
* updated README.md to mention "external-text-formatter" instead of "execute"
* updated "read-directory" test case reference file
* included library resolution test into "read-file" and "read-xml-file" test cases

* wraps result node construction and appends it to root node on destruction
* offers a simpler interface for common node construction patterns
* simplifies result node construction in all external function implementations
** most noticeable in FunctionReadDirectory
* expanded FunctionReadDirectory result nodes by name, extension, and full-path nodes

* test case base template contains the basic test case markup
** it was mostly created to include include-path resolution into the test cases
* improved transformer helper template by separating the external function call into its own variable

* order of items in a directory was varying across platforms which hindered testability
* they are now temporarily copied into a std::vector instance and then sorted using std::sort
* updated "read_directory" test case reference file accordingly

* "InputXSLT:transform" expects two input arguments and executes the given transformation into the given target file
** this function respresents a important step in the direction of making it possible to write an actual static site generator on top of InputXSLT using XSLT
* added basic "transform" test case
* updated README.md to include this new function

* the transformation is now provided with default parameters such as the target file and its parent directory
* added appropriate test case
** default_params
* test frontend now doesn't provide a "test" parameter anymore
* extracted parameter setter into separate member method "setParameters" of TransformationFacade

* the directories below "./test" contain test cases
** "transformation.xsl" and the expected result as "reference.xml"
** tests are performed by "check.sh"
*** returns diff on error
* this system enables simple verification of external function results
** way simpler than C++ unit tests would be in this scenario
* expanded cmake instructions to automatically execute the test cases
* old example transformation was removed