consistent naming scheme in result files

[sam81]

Several points:

• the name "condition" should be reserved to the experimental condition labels assigned by the user to the experimental conditions. For example result files should peraphs use "trial type" for differentiating between a "same" and a "different" trial in a same-different experiment. Likewise, in experiment with multiple constant stimuli, the "conditions" within a block should be consistently referred to as sub-conditions (this is already done for some paradigms).
• use of underscore or camel case should be consistent
• the nDifferences parameter should be renamed nSubconditions (this works for both number of adaptive tracks, and number of constant differences)