GtSample : add methods 'convertToSample' and 'updateConflicts' to handle...

GtSample : add methods 'convertToSample' and 'updateConflicts' to handle conflicts in the sample.mat, modified and fix methods 'merge' and 'mergeConflictsField'
GtPhase  : add methods 'initConflicts', 'resetSummary' and 'resetConflicts' and add logical expression 'obj.selectedGrains == true' to get only selected grains if looking for conflicts

Signed-off-by: Laura Nervo <laura.nervo@esrf.fr>

git-svn-id: https://svn.code.sf.net/p/dct/code/trunk@803 4c865b51-4357-4376-afb4-474e03ccb993