QueryParser treatment of unescaped internal operators [LUCENE-2916]

myfield:foo-bar and myfield:foo+bar are treated as myfield:"foo-bar" and myfield:"foo+bar"
but myfield:foo!bar is treated as myfield:foo -defaultfield:bar

Somewhat related, temp:70 works fine, but temp:-10 throws an exception. Many people hit this and figure out how to work around it relatively quickly, but just fixing the grammar to accept it might be better?

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Migrated from [LUCENE-2916](https://issues.apache.org/jira/browse/LUCENE-2916) by Yonik Seeley (@yonik), updated May 18 2016
Attachments: [LUCENE-2916-unescaped-negative.patch](https://apache.github.io/lucene-jira-archive/attachments/LUCENE-2916/LUCENE-2916-unescaped-negative.patch)

Start in the QueryParser grammar and review the attached LUCENE-2916-unescaped-negative.patch. Reproduce the foo-bar, foo+bar, foo!bar, and temp:-10 cases, then verify that unescaped internal operators and negative values parse consistently without changing the intended field semantics.

Written by the indexing model from the issue text.