Length profile improvements

[3nids]

• [x] export to DXF #20
• [x] print function #19
• [x] make sure the dock is visible when showing a profile #137
• [x] zoom to profile exten #128
• [x] provide manhole and section details (dimensions, depth, material, slope, etc) #17

[urskaufmann]

Some problems with the length profile:

• if you define it with two selections, you have not the same result as defining it with one selection: The surface-line (green line) is not correct at the start of the length profile and at the manhole, where the second selection starts (in the example the manhole ZE2J1).

• the information about the manhole showes no out-level available. But there is a level at the from-reach-point (this level is correct shown in the reach-information).

• the information about the manhole shows not the identifer but the obj_id