Neovim-friendly modification

The compile error message did not show in neovim, so this commit make
the message show and the run command will not be executed if there is
any message output after compiling.

This modification is only for C and C++.

autoload/runner.vim

@@ -94,12 +94,17 @@ endfunction
 " To do all subfunctions.
 function! runner#DoAll() abort
     if b:supported
-        call runner#Before()
-        call runner#Compile()
-        call runner#Run()
-        call runner#After()
+        try
+            call runner#Before()
+            call runner#Compile()
+            call runner#Run()
+            call runner#After()
+        catch /.*/
+            echo "Error: " . v:exception
+            return
+        endtry
     else
-        call runner#ShowInfo("   ❖  不支援  ❖ ")
+        call runner#ShowInfo("   ❖  not supported  ❖ ")
     endif
 endfunction
 
@@ -117,13 +122,9 @@ function! runner#Before() abort
     endif
     if g:runner_print_timestamp && b:ft !=# 'markdown'
         let l:date = strftime("%Y-%m-%d_%T")
-        silent execute "!printf '\033[31m' "
-        silent execute '!printf "\n<<<< \%s \%s >>>>\n" ' .
+        let l:info_msg = 'printf "\n<<<< %s %s >>>>\n" ' .
                     \l:date . " " . expand('%:t')
-        silent execute "!printf '\033[0m'"
-        if b:supported == 0
-            execute "!printf ''"
-        endif
+        echo system(l:info_msg)
     endif
 endfunction
 
@@ -133,19 +134,29 @@ endfunction
 function! runner#Compile() abort
     let b:tmp_name = strftime("%s")
     if b:ft ==# 'c'
-        silent execute "!" . g:runner_c_executable . " " .
-                    \ g:runner_c_compile_options .
-                    \ " % -o " .
+        let l:compile_cmd = g:runner_c_executable . " " .
+                    \ g:runner_c_compile_options . " " .
+                    \ expand('%:t') .
+                    \ " -o " .
                     \ b:tmp_dir .
                     \ b:tmp_name .
                     \ ".out"
+        let l:compile_msg = system(l:compile_cmd)
+        if len(l:compile_msg) != 0
+            throw l:compile_msg
+        endif
     elseif b:ft ==# 'cpp'
-        silent execute "!" . g:runner_cpp_executable . " " .
-                    \ g:runner_cpp_compile_options .
-                    \ " % -o " .
+        let l:compile_cmd = g:runner_cpp_executable . " " .
+                    \ g:runner_cpp_compile_options . " " .
+                    \ expand('%:t') .
+                    \ " -o " .
                     \ b:tmp_dir .
                     \ b:tmp_name .
                     \ ".out"
+        let l:compile_msg = system(l:compile_cmd)
+        if len(l:compile_msg) != 0
+            throw l:compile_msg
+        endif
     elseif b:ft ==# 'rust'
         if g:runner_rust_executable ==# "rustc"
             " Change output path if running in cygwin and use absolute path