connection.py: SSLError raises NetworkError intead of SSLVerficationError.

Closes chfoo/wpull#91.
app.py: Removes implicit span-hosts enable.

Superseded by strong redirect logic.
url.py: Relaxes URL query percent-encode escapes.

Closes chfoo/wpull#67. Closes chfoo/wpull#90.
readme.rst: Uses SVG version of Travis badge.
Revert "readme.rst: Uses SVG version of Travis badge."

This reverts commit fff82fde5e77b695fc15ec181782a885f334c219.

Re: chfoo/wpull#92

[ci skip]
writer.py: Appends suffix if file in directory path or filename is directory.

Closes chfoo/wpull#71.
item,processor: Adds LinkType constants.
database.py: Renames URLDBRecord→URL, URLStrDBRecord→URLString.
Implements --warc-dedup.

Closes chfoo/wpull#36
connection.py: Sets connection close on request header if not keep-alive.
connection.py: Uses ConnectionParams for Connection args.
hook: Adds engine_run() script callback. Exposes factory instance.
Implements --ignore-length.

Closes chfoo/wpull#44
options.py: Sorts the choices before printing.
Implements --output-document.

Closes chfoo/wpull#42
url.py: Double encodes hostname to work around issue 21103.

Closes chfoo/wpull#82
util.detect_encoding(): Continues loop if encoding is None.

Closes chfoo/wpull#96
util.py: Adds DeflateDecompressor.
connection.py: Supports deflate compression.
Implements --http-compression.

Closes chfoo/wpull#94.