Port before_v0.60/fuzzy, before_v0.60/ls-mods and before_v0.60/nu_101 (#845)

This PR is part of porting all old scripts #221 and includes a set of
modules:

- fuzzy -> `modules/fuzzy/fuzzy_command_search.nu`
- ls-mods -> `modules/ls-mods`: `ls-less.nu`, `ls-wide.nu` and
`ls-wide-with-color.nu`
- nu_101 -> `modules/nu_101`: `nothing.nu` and `inner_outer_loop.nu`

Edit: `fuzzy` and `nu_101` have been moved to `sourced`

sourced/nu_101/nothing.nu

@@ -0,0 +1,24 @@
+# This checks the -f switch to see if it was supplied
+# and tests the new $nothing variable
+def nada [
+    flat?
+] {
+    if $flat == null {
+        true
+    } else {
+        false
+    }
+}
+
+# This shows an alternate way to check for nothing
+def nada2 [
+    flat?
+] {
+    let flat = ($flat | is-empty)
+
+    if $flat {
+        true
+    } else {
+        false
+    }
+}