Documentation: update reserved names list

Added constants from 50dfe0175df02fe4aa243757bdf1b42fb9fc3169 (exit status codes)
Documentation: another update to reserved names list

Added missing user functions.
Also fixed a typo in common_functions.rst.
Merge pull request #2304 from vlakoff/develop

Documentation: update reserved names list
Fix a typo in changelog.rst

This missing space was broking the link generation.
Merge pull request #2305 from vlakoff/develop

Fix a typo in changelog.rst