Improve management of component requirements

[cwmeijer]

Requirements of component1 can be used by component2 without stating them. See documentation snippet below. That isn't the expected behavior I would say. A good fix would be to get the requirement elements out of the component element and put them in one or two levels higher in the xml.

The relevant documentation in the README.md:

It is important to notice that since all the commands are executed in the same execution folder, if a command in the sequence already 'linked' a file/folder (using <require> or <requirelist>) there is no need to do it again. An example XML configuration file:

<SeqCommands>
  <Component>
    <id> Executable1 </id>
    <requirelist>listimages.txt</requirelist>
    <require> inputfile1 inputfile2</require>
    <command> Executable1 *jpg inputfile1 inputfile2 -o outputfile1 </command>
  </Component>
  <Component>
    <id> Executable2 </id>
    <command> Executable2 inputfile1 outputfile1 </command>
  </Component>
</SeqCommands>