Support for file display with special characters in the name

[The command "cat"](http://en.wikipedia.org/wiki/Cat_%28Unix%29 "Concatenation of files?") was called to display a file content in a debug mode. The corresponding file name was passed in a way that the used parameter could be split into separate parts if [it contained special characters like spaces](https://github.com/coccinelle/coccinelle/issues/5 "Check handling of special characters?").

A name split could result in unwanted consequences.
* Different files would be referenced.
* The files would not be found with shorter names.
* Trailing text could eventually be interpreted as further shell commands with unknown side effects.

This situation can be fixed in the way that the specified file name will always be handled as a single parameter for the desired task. The content display can be performed by OCaml functions instead of an external program.