cln: Replace all uses of deprecated !include with include.

Also include a test which makes sure !include is still parsed.

examples/all.journal

@@ -1,8 +1,8 @@
 ; all years
 
-!include 2006.journal
-!include 2007.journal
-!include 2008.journal
-!include 2009.journal
-!include 2010.journal
-!include 2011.journal
+include 2006.journal
+include 2007.journal
+include 2008.journal
+include 2009.journal
+include 2010.journal
+include 2011.journal

examples/current.journal

@@ -1,4 +1,4 @@
 ; current/recent years
 
-;!include 2010.journal
-!include 2011.journal
+;include 2010.journal
+include 2011.journal

hledger/Hledger/Cli/Commands.hs

@@ -492,7 +492,7 @@ defaultyear_journal_txt = T.unlines
 --  ]
 
 -- journal4_str = unlines
---  ["!include \"somefile\""
+--  ["include \"somefile\""
 --  ,"2007/01/27 * joes diner"
 --  ,"  expenses:food:dining                    $10.00"
 --  ,"  assets:checking                        $-47.18"

hledger/test/journal/include.test

@@ -1,5 +1,5 @@
 # 1. nested includes in subdirectories
- mkdir -p b/c/d ; printf '2010/1/1\n (D)  1\n' >b/c/d/d.journal ; printf '2010/1/1\n (C)  1\n!include d/d.journal\n' >b/c/c.journal ; printf '2010/1/1\n (B)  1\n!include c/c.journal\n' >b/b.journal ; printf '2010/1/1\n (A)  1\n!include b/b.journal\n' >a.journal ; hledger -f a.journal print; rm -rf a.journal b
+ mkdir -p b/c/d ; printf '2010/1/1\n (D)  1\n' >b/c/d/d.journal ; printf '2010/1/1\n (C)  1\ninclude d/d.journal\n' >b/c/c.journal ; printf '2010/1/1\n (B)  1\ninclude c/c.journal\n' >b/b.journal ; printf '2010/1/1\n (A)  1\ninclude b/b.journal\n' >a.journal ; hledger -f a.journal print; rm -rf a.journal bG
 >>>
 2010-01-01
     (A)               1
@@ -90,3 +90,13 @@ _c
 _d
 >>>2
 >>>=0
+
+# 9. include using old !include directive
+ printf '2018/01/01\n (A)  1\n' >f.journal; hledger -f - print; rm -f f.journal
+<<<
+!include f.journal
+>>>
+2018-01-01
+    (A)               1
+
+>>>=0