Added several new functionalities to tree:

- Example nodes: Text nodes that write in a verbatim example enviroment.
- Dummy nodes: Nodes which can insert another node at a later point.
- Subsections: Creates subsections in the manual.
- EntryNode command: Searches by a chapter info list the correct entry point of a node.
- DocumentationNode command: Creates a node from a record with a type entry. Used by new parser.
Rewrote the parser to have a more structural layout

and add new commands simpler. New commands are:

@Chunk
Chunks texts in several parts

@BeginLevel
Begins a new level enviroment

@EndLevel
Ends a level enviroment

@Subsection
Adds a new subsection

@EndSubsection
Ends a subsection

@Example
Examples in a GAP-readable syntax can be added

@EndExample
Ends example enviroment
Wrapped the loops which define a bunch of functions

in functions itself to prevent the variable i
from being set while loading the package.
Made main documentation function use new parser.

Once the Declare*WithDoc functions are not used any
more, we can now get rid of this global variable.
Added documentation for new commands.
Added worksheet function.

AutoDoc is now able to produce so called worksheets.
Those are gap-readable files with examples in them,
which can be converted to a pdf by AutoDoc. New commands
for the parser are:

@Author
Adds an author to the pdf. Can be called several times.

@Title
Adds a title.
Increased version
Fixed some typos.
Fixed the bug which had ); appeared

at the end of the AutoDoc docu.
Closes #43.
Added documentation for the @Chunk command family.
Made authors displayed in worksheets.