Fix blank lines being required where they should not be. (#256)

[mlkirkpatrick]

This fixes #256. For people who add a blank line after every paragraph, they should see no change. This change is to support broader flexibility so that a blank line is no longer mandatory in situations where a block follows a paragraph.

Other implementations of GitHub flavor markdown do not depend on these blank lines, so I see no reason that markdown-to-jsx should. A more flexible implementation makes markdown easier to write with more reliable results.

This PR closes #266 as I moved it to its own branch.

[codecov[bot]]

Codecov Report

Merging #291 into master will not change coverage. The diff coverage is 100%.

@@           Coverage Diff           @@
##           master     #291   +/-   ##
=======================================
  Coverage   99.22%   99.22%           
=======================================
  Files           1        1           
  Lines         386      386           
  Branches       64       64           
=======================================
  Hits          383      383           
  Misses          3        3

Impacted Files	Coverage Δ
index.js	99.22% <100%> (ø)	:arrow_up:

---

Continue to review full report at Codecov.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update be04c33...b101558. Read the comment docs.

[joebnb]

could merge this ,pls it will fix #315 #405 #217 #279 .... a lot of issues

[rdoughty]

Any chance of merging this?