Add support for merging timeSeries

[x-malet]

must support:

• different parameters
• different time start/end
• different time steps
• comparison between same parameter for different probes ==> the Dataframe needs to be remodeled
• date/time transformation
• select by probe/channel/time (all or separate)

[x-malet]

branch 15-issues-merge-timesseries created for this issue