Add insert, remove and update methods to multi_index (and index)

[mikelik]

Change Description

Resolves #135
Add insert, remove and update methods to multi_index

API Changes

• API Changes

For multi_index there are 3 new methods: insert (alias for emplace), remove (alias for erase), update (alias for modify).

Documentation Additions

• Documentation Additions

If there is documentation for multi_index 3 new methods should be added. It might be in separate repo docs.

[dimas1185]

please address @jolly-fellow comments, not critical but will reduce verbosity

[ericpassmore]

Note:start
group: STABILITY
category: INTERNALS
summary: Add alternate names for operations to insert, remove, and update indexes.
Note:end