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	supply1	supply2	supply3

1	0	20	27	

2	0	-4	0		

3	0	0	0	

4	0	0	0	

5	0	9	0	

6	0	-6	0	

7	0	0	0	

8	0	0	0	

9	0	3	0	

10	0	-2	0	

11	0	0	0		

12	0	-20	-27	

@arcs

		cost	capacity	lower1	lower2

1	2	70	11		0	8

1	3	150	3		0	1

1	4	80	15		0	2

2	8	80	12		0	0

3	5	140	5		0	3

4	6	60	10		0	1

4	7	80	2		0	0

4	8	110	3		0	0

5	7	60	14		0	0

5	11	120	12		0	0

6	3	0	3		0	0

6	9	140	4		0	0

6	10	90	8		0	0

7	1	30	5		0	0

8	12	60	16		0	4

9	12	50	6		0	0

10	12	70	13		0	5

10	2	100	7		0	0

10	7	60	10		0	0

11	10	20	14		0	6

12	11	30	10		0	0

@attributes

source	1

target	12

@end