add: New entity "Resel per voxels map"
add: conjunction activity
add: conjunctionType attribute

add conjunctionType attribute to specify global null or conjunction
add: labelId attribute in clusters

nidm:labelId corresponds to the value associated with a particular
cluster in the `nidm:clusterLabels` map (stored under the excursion_set
entity)
conjunctionType in nidm namespace
`conjunction` as entity of type `nidm:inference`

conjunctions are now modelled using an entity of type nidm:inference,
with attribute nidm:statisticalTest set to nidm:conjunction (or other
option for conjunctions)
fix: typos and update png graphs
inference used RPV map (non-stationarity only)
`reselsPerVoxelMap` in `spm` namespace

According to comment by @nicholst, the RPV map is specific to SPM,
`reselsPerVoxelMap` therefore needs to be in `spm` namespace.
Specify whether stationary of non-stationary RFT is used

Update `pValueFWER` in `pValuesNonStationaryFWER` (in this example we
suppose we are using non-stationarity, in case of stationarity we would
have used `pValuesStationaryFWER` instead)
Minimal example for conjunction

As suggested on NIDASH-DDWG call, March 3rd, 2014.
Example of inference activities

A proposition to encode (global null/conjunction/inference) and the
degree of global null.
add: void.ttl example for xnat projects
add: core void description of the projects in a databse
Renaming of "Global null Inference" into "k-Conjunction inference"

- Renaming of "Global null Inference" into "k-Conjunction inference"
- "k-Conjunction inference" in the spm namespace
rebasing, conflicts in png only
Recompute graphs
typo: remove duplicate used relationship
typo: use same type 'nidm:maskMap' for all mask entities
Update png graphs