lib: add -P short flag for --pending (#564)

doc/lib.m4

@@ -140,7 +140,7 @@ m4_define({{_reportingoptions_}}, {{
 `-C --cleared`
 : include only cleared postings/txns
 
-`--pending`
+`-P --pending`
 : include only pending postings/txns
 
 `-U --uncleared`

hledger/Hledger/Cli/CliOptions.hs

@@ -140,7 +140,7 @@ reportflags = [
  ,flagNone ["date2"]         (setboolopt "date2") "show, and make -b/-e/-p/date: match, secondary dates instead"
 
  ,flagNone ["cleared","C"]   (setboolopt "cleared") "include only cleared postings/txns"
- ,flagNone ["pending"]       (setboolopt "pending") "include only pending postings/txns"
+ ,flagNone ["pending","P"]   (setboolopt "pending") "include only pending postings/txns"
  ,flagNone ["uncleared","U"] (setboolopt "uncleared") "include only unmarked postings/txns"
  ,flagNone ["real","R"]      (setboolopt "real") "include only non-virtual postings"
  ,flagReq  ["depth"]         (\s opts -> Right $ setopt "depth" s opts) "N" "hide accounts/postings deeper than N"

site/faq.md

@@ -181,6 +181,8 @@ or [balance assertions](manual.html#assertions-and-ordering).
 - in hledger version 1.3 onward, -U/--uncleared does not match pending things.
   (#564)
 
+- hledger's -P flag is short for --pending. Ledger uses it for grouping by payee. 
+
 ### Future ?
 
 There is a [ledger4](https://github.com/ledger/ledger4) repo on