Nested section support

[Ext3h]

Addresses

Changes:

• Sections can now be properly nested
• Graceful handling of improperly closed sections
• collapsed=true section option is honored
• Nested sections have a slight indentation for better readbility of long logs
• Get rid of empty lines
• Switch to monospace font to better align with how the logs are shown on Gitlab
• Reduced memory and CPU footprint by a lot

Bug fixes:

• Durations are computed correctly for nested sections
• Web extension has no access to window.location query strings, so build href without path
• Section options no longer break duration calculation (start_section with options have no duration calculated #37)
• Deal with overly long lines in formatted output
• Avoid horizontal scroll bars