Fix SymbolProc autocorrect with multiple offenses

When there were multiple offenses for the SymbolProc cop (e.g.
`coll.map { |s| s.upcase }.map { |s| s.downcase }`) the cop would
raise an error: `Parser::Source::Rewriter detected clobbering`.

Digging into relevant commits I found some inspiration from
@jonas054 (#569). This commit changes the autocorrect for the
`SymbolProc` cop to be a little more precise in determining what to
correct. There's a new spec that I wrote that fails on master and
passes on this branch.
Merge pull request #1456 from jcarbo/fix-multiple-symbol-proc

Fix SymbolProc autocorrect with multiple offenses
Fix Style/ElseAlignment Cop error on def/rescue/else/ensure/end.
Merge pull request #1457 from oneamtu/master

Fix Style/ElseAlignment Cop error on def/rescue/else/ensure/end.
Fix %W[] auto corrected to %w(]
Ignore contents of backticks in changelog spec
Add EmptyLinesAroundBlockBody cop

There were a few existing cops for preventing/enforcing newlines
around the body of classes, methods, and modules. There wasn't one
for blocks (especially relevant for rspec!) so this adds one.
Fix EmptyLinesAroundBlockBody offenses
[Fix #1459] Handle parentheses around condition in NegatedWhile

In autocorrect, not handling the parentheses produced incorrect
code. Sematically different and/or syntactically wrong.
Merge pull request #1463 from jcarbo/empty-lines-around-block-body

Add EmptyLinesAroundBlockBody cop
Merge pull request #1464 from jonas054/1459_fix_NegatedWhile

[Fix #1459] Handle parentheses around condition in NegatedWhile
Merge pull request #1462 from toy/fix_unneeded_capital_w_autocorrection

fix `%W[]` auto corrected to `%w(]`
[Fix #1465] Handle properly code like "#$1" in PerlBackrefs's autocorrect
Handle properly code like "#$:" in SpecialGlobalVars's autocorrect
Fix a typo
[Fix #1466] Allow underscored parameters in SingleLineBlockParams

Allow leading underscores on parameter names, but check
them in the normal way apart from the underscores.
Merge pull request #1469 from jonas054/1466_unused_reduce_args

[Fix #1466] Allow underscored parameters in SingleLineBlockParams
Update README.md
Merge pull request #1471 from jeffreyjackson/patch-1

Update README.md
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