better algorithm for SUM
Merge pull request #19 from CrowdProcess/flatten_values_in_IRR

flatten values in IRR formula
flatten SUMIF range
Merge pull request #20 from CrowdProcess/flatten_ranges

Flatten ranges
make SUMIFS work
flatten SUMSQ
flatten arrays of SUMX2MY2
flatten the rest of SUM formulas
flatten arguments of AVEDEV
flatten arguments of AVERAGE
flatten arguments of AVERAGE and AVERAGEA, ignore non numbers in AVERAGE, add utility NUMBERS function that returns the numbers in an array
test true and false in AVERAGEA
Fix FLOORPRECISE
Minor changes
V0.0.28
flatten AVERAGEIF
less eval in AVERAGEIFS
cannot make AVERAGEIFS work with multi dimensional arrays, comment that
COUNT must only count non empty cells, and admit multi-dimensional arrays
do not admit ''