Add configuration to preserve line breaks in notes #902

Is your feature request related to a problem? Please describe.
#901
Blinko removes extra line breaks by default which makes notes difficult to read when not using markdown for formatting.

Describe the solution you'd like
Add a configuration toggle that sets the breaks={true} option in ReactMarkdown so that extra line breaks in notes are preserved.

Additional context
I write notes in plain text while and don't have time for extensive formatting or makrdown. I use line breaks to create headers and separate blocks of text. I would like line breaks preserved without using markdown.