Improve Nim layer

- Add support for better completion using Nim's IDE tool, `nimsuggest`.
- Add key binding for goto definition and jump back.
- Eldoc integration (with the nimsuggest-mode)
- Update documentation.

layers/+lang/nim/README.org

@@ -5,24 +5,33 @@
 * Table of Contents                                         :TOC_4_gh:noexport:
  - [[#description][Description]]
  - [[#install][Install]]
-   - [[#layer][Layer]]
  - [[#working-with-nim][Working with Nim]]
    - [[#nim-commands-start-with-m][Nim commands (start with =m=):]]
 
 * Description
+This layer provides the following features for Nim:
 
-This layer adds support for nim (nimrod).
+- Code completion.
+- Jump to definition.
+- Syntax checking.
 
 * Install
-** Layer
 To use this configuration layer, add it to your =~/.spacemacs=. You will need to
 add =nim= to the existing =dotspacemacs-configuration-layers= list in this
 file.
 
+For syntax checking, the =syntax-checking= layer must also be added.
+
+For all the features to work properly, =nimsuggest= must be installed properly
+and =nimsuggest= binary must be in $PATH.
+
 * Working with Nim
 
 ** Nim commands (start with =m=):
 
-| Key Binding | Description                |
-|-------------+----------------------------|
-| ~SPC m c r~ | nim compile --run main.nim |
+| Key Binding        | Description                |
+|--------------------+----------------------------|
+| ~SPC m c r~        | nim compile --run main.nim |
+| ~SPC g g~ or ~M-.~ | Jump to definition         |
+| ~SPC g b~ or ~M-,~ | Jump back                  |
+|--------------------+----------------------------|

layers/+lang/nim/packages.el

@@ -5,7 +5,8 @@
         nim-mode))
 
 (defun nim/post-init-company ()
-  (spacemacs|add-company-hook nim-mode))
+  (spacemacs|add-company-hook nim-mode)
+  (spacemacs|add-company-hook nimscript-mode))
 
 (defun nim/post-init-flycheck ()
   (spacemacs/add-flycheck-hook 'nim-mode))
@@ -17,12 +18,17 @@
 (defun nim/init-nim-mode ()
   (use-package nim-mode
     :defer t
-    :init (when (configuration-layer/package-usedp 'company)
-            (push 'company-nim company-backends-nim-mode))
+    :init
+    (when (configuration-layer/package-usedp 'company)
+      (push 'company-capf company-backends-nim-mode))
+    (add-hook 'nim-mode-hook 'nimsuggest-mode)
     :config
     (progn
       (defun spacemacs/nim-compile-run ()
         (interactive)
         (shell-command "nim compile --run main.nim"))
+
       (spacemacs/set-leader-keys-for-major-mode 'nim-mode
-        "cr" 'spacemacs/nim-compile-run))))
+        "cr" 'spacemacs/nim-compile-run
+        "gg" 'nimsuggest-find-definition
+        "gb" 'pop-tag-mark))))