Fix two bugs in findLast and findLastIndex

This fixes two issues:

(1) If only the first element of an array matched the predicate, neither findLast nor findLastIndex
would report is as present.

(2) More critically, if queried with an empty array, both functions would enter into an infinite
loop.
Fix a critical bug in R.mathMod
Merge pull request #334 from markprzepiora/fix-mathmod

Fix a critical bug in R.mathMod
Merge pull request #333 from markprzepiora/fix-find-last-bugs

Fix two bugs in findLast and findLastIndex
per @megawac, decrement ramda-style. keep new tests
Merge pull request #336 from ramda/master

per @megawac, decrement ramda-style. keep new tests
rename fork; rename param to func; some doc fixes

check in test file too
Merge pull request #337 from ramda/master

rename fork; rename param to func; some doc fixes
Update ramda.js
Merge pull request #338 from ThomasDeutsch/patch-1

Update ramda.js - fixed example (R.reduce)
Prepare for 0.4.2
Prepare for 0.4.3
Fix a bug in R.skip

Calling `R.skip(n, list)` for `n >= list.length` would result in an error being thrown. Instead,
this commit causes an empty array to be returned.
Merge pull request #340 from markprzepiora/fix-skip-bug

Fix a bug in R.skip
Skipping extra call to _slice when called with one arg