Changelog update and release of 3.19.0 (#238)

More elaborated error message if TGDB fails

Version 3.18.4

Version 3.18.3

Fix QString templates (#206), fix extensions (#205) (#207)

plus:
- zxinfo scraping: try with hash first
- zxinfo scraping: enable (YYYY) hint in filename / alias
- zxinfo scraping: doc update
- some edge cases fixed

Version 3.18.1

Cast to underlying type to use numeric operators. Fixes #198 (#199)

Version 3.17.5 and doc update (#173)

* General: replaced [here] links with contextual link text, fixed broken links
* added INSTALLATION.md
* FAQ: added two questions with answers
* PLATFORMS: added section for adjusting platform config
* CONFIGINI: added usage level to  the config file options
* plus many smaller edits and corrections

Fix path handling for ES frontend and other edge case fixes (#165)

* revert path logic to inputFolder instead gameListFolder for ES

which contains:
- handle pegasus frontend and path differently than other frontends
- workaround for ES' habit to rewrite absolute home path with ~ when absolute paths are used in the gamelist.
- fix edge case when two configs are changed and a new game is added to a game list simultaneously
- cover edge case when inputfolder is specific symlink
- refactorings when relative path is provided
- updated path processing documentation

further fixes non related to path handling: 
- print warning when attractmode romlist folder not existing
- mute manuals folder output when the frontend does not support it (e.g. pegasus)
- reworked documentation on unattend and unattendskip
- Fix gamelist entry, when flags skipExistingVideos and skipExistingMedia are used

Fixes regression of #160