Added very basic support for autocompleting modules

Closes #15
Relates #7

autoload/modules.vim

@@ -0,0 +1,82 @@
+if exists("s:loaded")
+    finish
+endif
+let s:loaded = 1
+
+
+function! modules#FindImportLocation()
+    return searchpos("^import")
+endfunction
+
+function! modules#HasImports()
+    let [l, c] = modules#FindImportLocation()
+    return l != 0 && c == 1
+endfunction
+
+function! modules#IsMultilineImport()
+    if modules#HasImports()
+        let [l, c] = modules#FindImportLocation()
+        return indent(l + 1) > 0
+    endif
+    return 0
+endfunction
+
+function! modules#AddImport(module)
+    let imports = modules#GetImports()
+    let [begin, end] = modules#ImportLineRange()
+    exec ":" . begin . "," . end . "d"
+
+    let idx = begin - 1
+    call add(imports, a:module)
+    call append(idx, "import")
+    for import in imports
+        let wsstr = ""
+        for wr in range(0, &sw)
+            let wsstr .= " "
+        endfor
+
+        let idx += 1
+        call append(idx, wsstr . import . (idx - begin + 1 < len(imports) ? "," : ""))
+    endfor
+endfunction
+
+function! modules#ImportLineRange()
+    let [l, c] = modules#FindImportLocation()
+    if l == 0
+        return [0, 0]
+    endif
+
+    let idx = 2
+    while idx < line("$") && indent(idx) > 0
+        let idx += 1
+    endwhile
+    return [l, idx - 1]
+endfunction
+
+function! modules#GetImports()
+    if !modules#HasImports()
+        return []
+    endif
+
+    let [begin, end] = modules#ImportLineRange()
+    let lines = getline(begin, end)
+    return filter(split(substitute(join(lines, ""), ",", "", "g"), " "), 'v:val !~ "^ *$"')[1:-1]
+endfunction
+
+function! modules#ImportMap(imports)
+    let result = {}
+    for import in a:imports
+        if import !~? ".*\/system\/.*" && import !~? ".*\/deprecated\/.*"
+            let result[fnamemodify(import, ":t:r")] = import
+        endif
+    endfor
+    return result
+endfunction
+
+" function! modules#FindLocalImports()
+"     " return ImportMap(globpath(g:nvim_nim_deps_nim, "**/*.nim", 0, 1))
+" endfunction
+
+function! modules#FindGlobalImports()
+    return modules#ImportMap(globpath(g:nvim_nim_deps_nim, "**/*.nim", 0, 1))
+endfunction