Epcy

* Now EPCY can use design file (`-d`) with numerical condition (like `--query 1 --ref 2`)

- Add an output file (like log_cpm.tsv, ...), for downstream analysis
- replace ".xls" by ".tsv", as epcy output files are tabulated files.
- remove "np.bool", not availlable with numpy new version.

* remove unused parameter --nolog
* fix epcy profile, by adding --norm
* fix seaborn dependency

* Fix *epcy explore* tool (for advanced users, no detailed documentation available)

* EPCY output:
- rename mean_query and mean_ref into mean_log2_query and mean_log2_ref
* Add --norm --nolog parameters for *epcy pred* command:
- to manage more easily different types of quantitative data

Add shuffle option to estimate a null distribution and find a threshold.