הורדת גרסאות קודמות של Manta

- Simpler auto-update implementation.
Now the users don't even need to think about this (PR #262).
- New screenshots on README (PR #258).
- Added GitHub contribution guidelines (PR #226).
- Updated Wiki
- Added German date format (PR #247).
- Added the ability to debug production app (PR #235).
- Integrated DevTron to the devTools window (PR #238).
- Added Linux launcher to electron-builder config (PR #240).
- Fixed an issue where the notification is overlayed by the exportDir input (PR #251).
- Added missing translation of validation message for invalid custom invoiceID (PR #249).
- Display TaxID in the invoice templates (PR #255).
- Fixed an issue where the item quantity is rounded to the nearest whole number (PR #260).
- Changes in profile now will reflect immediately in the templates (PR #245).