add [feature]: mastodon in social menu

Similar to MunifTanjim#174 but with a nicer icon (taken from the Mastodon [press
kit](https://source.joinmastodon.org/mastodon/joinmastodon/blob/master/public/press-kit.zip)
and simplified with Inkscape).

data/config/default/widgets.toml

@@ -21,7 +21,7 @@ mirror = ""
 
 [social_menu]
 title = ""
-platforms = ["github","facebook","twitter","instagram","email","codepen","gitlab","linkedin","telegram","google_scholar","youtube"]
+platforms = ["github","facebook","twitter","mastodon","instagram","email","codepen","gitlab","linkedin","telegram","google_scholar","youtube"]
 
 [taxonomy_cloud]
 title = ""

data/theme.toml

@@ -6,6 +6,7 @@ github = "https://github.com/"
 gitlab = "https://gitlab.com/"
 instagram = "https://instagram.com/"
 linkedin = "https://linkedin.com/in/"
+mastodon = "https://"
 twitter = "https://twitter.com/"
 telegram = "https://t.me/"
 google_scholar = "https://scholar.google.com/citations?user="

exampleSite/config.toml

@@ -84,6 +84,7 @@ twitter = "MunifTanjim"
 telegram = "MunifTanjim"
 google_scholar = "qc6CJjYAAAAJ"
 youtube = "UCT-U0rNerYxItGcuoPX-WYA"
+mastodon = ""
 
 [params.comments]
 enable = false

layouts/partials/svg/icons.html

@@ -73,5 +73,7 @@
   {{ else if eq "search" . }}
   <circle cx="11" cy="11" r="8" />
   <line x1="21" y1="21" x2="16.65" y2="16.65" />
+  {{ else if eq "mastodon" . }}
+  <path d="m 20.745,13.949 c -0.591,1.823 -2.546,2.713 -4.289,3.077 -2.768,0.533 -5.643,0.438 -8.388,-0.183 -0.140,1.321 0.850,2.729 2.230,2.797 1.689,0.327 3.447,0.194 5.097,-0.269 0.248,0.941 0.050,2.126 -1.167,2.049 C 11.651,22.102 8.861,21.840 6.392,20.878 4.221,19.766 3.330,17.246 3.096,14.959 2.769,12.414 2.818,9.835 2.961,7.280 3.249,5.132 4.798,2.984 7.063,2.698 10.408,1.982 13.903,2.070 17.247,2.738 c 1.603,0.382 2.907,1.631 3.426,3.185 0.760,2.146 0.420,4.463 0.271,6.679 -0.051,0.451 -0.115,0.901 -0.199,1.347 z" />
   {{ end }}
 </svg>