Merge branch 'master' into sakia020

res/i18n/ts/cs_CZ.ts

res/i18n/ts/de_DE.ts

res/i18n/ts/es_ES.ts

res/i18n/ts/fr_FR.ts

res/i18n/ts/it_IT.ts

res/i18n/ts/pl_PL.ts

res/i18n/ts/pt_BR.ts

res/i18n/ts/ru_RU.ts

src/sakia/core/money/relative_zerosum.py

src/sakia/gui/preferences.py

update_ts.py