Include g:tpipeline_size in debug info

We need this variable occasionally for debugging, so let's remove one
roundtrip by including it by default.

This patch also adds a test to make sure that debug info is always
available in vim and neovim.

Author: vimpostor

autoload/tpipeline/debug.vim

@@ -32,6 +32,7 @@ func tpipeline#debug#info()
 
 		let result.native_str = native.str
 		let result.native_highlights = native.highlights
+		let result.tpipeline_size = g:tpipeline_size
 	else
 		let brand = 'vim'
 		let version_info = v:versionlong

tests/test_general.vim

@@ -195,3 +195,8 @@ func Test_quoted_strings()
 	call Read_socket()
 	call assert_equal(string(g:ReturnNumber()), Strip_hl(s:left))
 endfunc
+
+func Test_can_debug()
+	let info = tpipeline#debug#info()
+	call assert_true(len(info))
+endfunc