standardizes the call of icons. Avoids switching to code mode for entry

syntax : {up icon=icone_name}
Important : indicate in prefs.ini the prefix for the icon font installed on the site

🟩 upbtn-makefile PREFS.INI :
options (default) : prefix=fa fa- | fontname=Font Awesome 6 Free
lomart-logo : icon=images/lomart.jpg, 64px | class=bd-rouge | size=48px
up-logo : src=images/up-lego.png | size=48px
up-logo-2 : icon=images/up-lego.png,48px | class=bd-rouge mb1
icons : etoile=Ux2b50,24px | smiley=Ux1F600 | un=Ux2776 | deux=Ux2777 | trois=Ux2778 | quatre=Ux2779 | cinq=Ux277A | six=Ux277B | sept=Ux277C | huit=Ux277D | neuf=Ux277E | info2=Ux1F6C8,steelblue | fleche=Ux27A7,green | fleche-2=Ux279C,green | param=cog,steelblue,24px | france=plugins/content/up/assets/img/france.png,2rem | belgique=plugins/content/up/assets/img/belgique.png,2rem | canada=plugins/content/up/assets/img/canada.png,2rem | gb=plugins/content/up/assets/img/gb.png,2rem | usa=plugins/content/up/assets/img/usa.png,2rem | note=plugins/content/up/assets/img/ico-crayon.png,20px | idee=plugins/content/up/assets/img/ico-idee.png,20px | vrai=plugins/content/up/assets/img/ico-vrai.png,20px | faux=plugins/content/up/assets/img/ico-faux.png,20px | info=plugins/content/up/assets/img/ico-info.png,20px | danger=plugins/content/up/assets/img/ico-danger.png,20px