Log Message:
py-nbconvert: updated to 5.5.0

5.5.0:

New Features
- IPyWidget Support
- A new ClearMetadata Preprocessor is available
- Support for pandoc 2
- New, and better, latex template

Fixing Problems
- Refactored execute preprocessor to have a process_message function
- Fixed OOM kernel failures hanging
- Fixed latex export for svg data in python 3
- Enabled configuration to be shared to exporters from script exporter
- Make latex errors less verbose
- Typo in template syntax
- Improved attachments +fix supporting non-unique names
- PDFExporter "output_mimetype" traitlet is not longer 'text/latex'
- FIX: respect wait for clear_output
- address deprecation warning in cgi.escape
- Correct inaccurate description of available LaTeX template
- Fixed kernel death detection for executions with timeouts
- Fixed export names for various templates

Deprecations
- Dropped support for python 3.4
- Removed deprecated export_by_name

Testing, Docs, and Builds
- Added tests for each branch in execute's run_cell method
- Mention formats in --to options more clearly
- Adds ascii output type to command line docs page, mention image folder output
- Simplify setup.py
- Use utf-8 encoding in execute_api example
- Upgrade pytest on Travis
- Fix LaTeX base template name in docs
- Updated release instructions based on 5.4 release walk-through
- Fixed broken link to jinja docs