home: vim: ftdetect: switch to lua

It looks like `vim.filetype.add` is smarter about "local.am".

For some reason opening an *empty* Tiger file results in a backtrace...

home/vim/ftdetect/automake.lua

@@ -0,0 +1,6 @@
+-- Use Automake filetype for `local.am` files, explicit `set` to force override
+vim.filetype.add({
+    filename = {
+        ["local.am"] = "automake",
+    },
+})

home/vim/ftdetect/automake.vim

@@ -1,2 +0,0 @@
-" Use Automake filetype for `local.am` files, explicit `set` to force override
-au BufNewFile,BufRead local.am set filetype=automake

home/vim/ftdetect/direnv.lua

@@ -0,0 +1,6 @@
+-- Use bash filetype for `.envrc` files
+vim.filetype.add({
+    filename = {
+        [".envrc"] = "bash",
+    },
+})

home/vim/ftdetect/direnv.vim

@@ -1,2 +0,0 @@
-" Use bash filetype for `.envrc` files
-au BufNewFile,BufRead .envrc setfiletype bash

home/vim/ftdetect/tiger.lua

@@ -0,0 +1,7 @@
+-- Use Tiger filetype for programs and header files
+vim.filetype.add({
+    extension = {
+        tig = "tiger",
+        tih = "tiger",
+    },
+})

home/vim/ftdetect/tiger.vim

@@ -1,3 +0,0 @@
-" Use Tiger filetype for programs and header files
-au BufNewFile,BufRead *.tig setfiletype tiger
-au BufNewFile,BufRead *.tih setfiletype tiger

home/vim/ftdetect/tikz.lua

@@ -0,0 +1,6 @@
+-- Use LaTeX filetype for TikZ files
+vim.filetype.add({
+    extension = {
+        tikz = "tex",
+    },
+})

home/vim/ftdetect/tikz.vim

@@ -1,2 +0,0 @@
-" Use LaTeX filetype for TikZ files
-au BufNewFile,BufRead *.tikz setfiletype tex