Rename and improve fromPromise

[Avaq]

• Merges master to get @SoullessWaffle's improvements to the documentation
• Renames fromPromise to encaseP.
• Adds tryP, the nullary version of encaseP.
• Prevents Promises from catching (and subsequently silently ignoring) errors thrown synchronously in transformations following the encasement of a Promise.

This last change is perhaps best explained through code:

Before:

> Future.tryP(_ => Promise.resolve(1)).map(x => { throw new Error('kaputt') }).value(console.log)
(node:8546) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): Error: kaputt

After:

> Future.tryP(_ => Promise.resolve(1)).map(x => { throw new Error('kaputt') }).value(console.log)
Future.tryP(_ => Promise.resolve(1)).map(x => { throw new Error('kaputt') }).value(console.log)
                                                ^
Error: kaputt

Closes #92

[codecov-io]

Codecov Report

Merging #98 into 6.0 will not change coverage.
The diff coverage is 100%.

@@         Coverage Diff         @@
##            6.0    #98   +/-   ##
===================================
  Coverage   100%   100%           
===================================
  Files        36     36           
  Lines       962    972   +10     
===================================
+ Hits        962    972   +10

Impacted Files	Coverage Δ
src/encase-p.js	100% <100%> (ø)

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