Implemented destroySynapse, started destroySegment and tests
Implemented destroySegment
Using googletest assertions instead of deprecated ones
Removed TODO
Pass by value instead of reference wherever possible
Revert "Pass by value instead of reference wherever possible"

This reverts commit 76cbea1fdeee1ca6c2bf5c11cbd820d3f612e21c.
Implemented leastRecentlyUsedSegment
Added TODO
Added parameter to constructor: maxSegmentsPerCell
Reusing segments when hitting the limit
Fixed bug with numSegments and numSynapses
Merge with master
Conventions
Using return parameter in dataForSegment
Made dataForSynapse use return parameter
Revert "Made dataForSynapse use return parameter"

This reverts commit fe1327c91dd7fcd1334d21b57abeeac3b310e0ac.
Revert "Using return parameter in dataForSegment"

This reverts commit 062f303987ec9724016b7aa46be0068574eb1c81.
Following convention
Add .capnp.h files to installed includes directory.
Cleanup