Simplify definition of counted parameters

[VGPReys]

Desired feature/enhancement

It would be simpler to compute on the fly some of the counted parameters.

Motivation

Simplify the configuration files with unnecessary parameters

Description

The idea is to go from:

[flexref]
nfle = 2    # Useless parameter, as we could compute it from the number of defined flexible segments.
fle_sta_1 = 1
fle_end_1 = 10
fle_seg_1 = "A"
fle_sta_2 = 1
fle_end_2 = 10
fle_seg_2 = "B"

to:

[flexref]
fle_sta_1 = 1
fle_end_1 = 10
fle_seg_1 = "A"
fle_sta_2 = 1
fle_end_2 = 10
fle_seg_2 = "B"

[sverhoeven]

Nice, this will also simplify the the workflow-builder and haddock3-webapp.