refactored TemporalEventPiecewiseLinear
now has a membership_function of type FunctionPiecewiseLinear
TemporalEventTrapezium functional again
fixed 'plot' of TemporalInstance
function_convolution_generic functional
generic_formulas now does what dario wanted to do
wrote 'mean' for ProbabilityDistributionPiecewiseLinear
wrote '+' operand for TimeInterval
generic_formulas almost done
Merge branch 'master' of github.com:opencog/opencog
Merge pull request #380 from keyvan-m-sadeghi/master

Interval Algebra, new formulas