Update README.md

[update] increased robustness of correlation picker. If autoPyLoT fails on the stacked trace it tries to pick other stacked traces. Ignoring failed autoPyLoT picks can manually be set if they are not important (e.g. when only pick differences are important)

[update] re-implemented code that was lost when corr_pick was integrated in pylot. Use all reference-pick-corrected theoretical picks as correlation reference time instead of using only reference picks

Update README.md

[bugfix] explicitly pass parameters to "picksdict_from_picks" to calculate pick weights. Otherwise no weights could be calculated. Closes #40

[bugfix] changed default behavior of PylotParameter class to use default Parameter if called without input parameters. Related to #40

[minor] small code fixes

[bugfix] flawed logic after parameter renaming corrected

[minor] increased robustness of correlation algorithm for unknown exceptions...

[bugfix] reverting code from commit 3069e7d5. Checking for coordinates in dataless Parser IS necessary to make sure correct Metadata were found. Fixes #37.

[update] small changes increasing code robustness

[minor] adding missing image to doc

[minor] modify README

Merge remote-tracking branch 'origin/develop' into develop

[update] add description for pick correlation algorithm