first iteration towards element access through memory
test script..
Merge branch 'master' into memaccess_elements
Update Madx.get_element (not using RPyC in master)
Merge branch 'memaccess_elements' into active-sequence

Conflicts:
	src/cern/cpymad/libmadx.pxd
Merge branch 'active-sequence' into memaccess_elements

Conflicts:
	src/cern/cpymad/model.py
Return list of element dicts from get_elements
Move get_elements to Sequence class

All sequence specific information should be retrieved directly from the
proxy object.
Split get_active_sequence() function from get_sequence
Revert "test script.."

This reverts commit 65f05e93edc2e9a7033edb8d54bd25b04c32d084.
Remove the subsequence code branch from get_elements

In my tests, I was unable to create with an in-memory represenation
containing a subsequence. So, remove this code branch for now (saves a
LOT of complexity actually, since this wasn't well thought out yet). If
this is ever needed, it can be added later on.
Use .name and .at from the node

If the element does not have a personal name but occurs multiple times
within a sequence (or LINE!), the element.name will be ambiguous and the
element.at will be incorrect.
Return floats for trivial Expressions

For expressions like "0 ", there is no use justifying the overhead of
dealing with an Expression object.
Clean up LookupDict, TfsDict, TfsSummary classes

There is a minor patch (beyond style) that may affect runtime behaviour:

- converted to new-style classes (default in python3)
- Attribute and key access for TfsTable.names will now both yield the
  same result.
Return Element objects from Sequence.get_elements
Merge branch 'memaccess_elements' into active-sequence
Remove retdict from Table return value
Return `Table`s from madx.survey()
Don't add unused columns to list
Fix incorrect member variable name