Various doc improvements for graph adaptors (#67)

- Add notes about modifying the adapted graphs through adaptors
if it is possible.
- Add notes about the possible conversions between the Node, Arc and
Edge types of the adapted graphs and the adaptors.
- Hide the default values for template parameters (describe them
in the doc instead).
- More precise docs for template parameters.
- More precise docs for member functions.
- Add docs for important public typedefs.
- Unify the docs of the adaptors.
- Add \relates commands for the creator functions.
- Fixes and improvements the module documentation.

 @nodes

 label

 0

 1

 2

 3

 4

 5

 6

 7

 8

 9

 @arcs

 		label	capacity

 0	1	0	20

 0	2	1	0

 1	1	2	3

 1	2	3	8

 1	3	4	8

 2	5	5	5

 3	2	6	5

 3	5	7	5

 3	6	8	5

 4	3	9	3

 5	7	10	3

 5	6	11	10

 5	8	12	10

 6	8	13	8

 8	9	14	20

 8	1	15	5

 9	5	16	5

 @attributes

 source 1

 target 8