imp: journal: remove the "adjacent conversion postings" check again

I find that single conversion postings are sometimes needed, eg with
paypal.

hledger-lib/Hledger/Read/Common.hs

@@ -337,7 +337,8 @@ journalFinalise iopts@InputOpts{..} f txt pj = do
     when strict_ $ do
       journalCheckAccounts j                     -- If in strict mode, check all postings are to declared accounts
       journalCheckCommodities j                  -- and using declared commodities
-      journalCheckPairedConversionPostings j     -- check conversion postings are in adjacent pairs
+      -- journalCheckPairedConversionPostings j     -- check conversion postings are in adjacent pairs
+                                                    -- disabled for now, single conversion postings are sometimes needed eg with paypal
 
     return j
 

hledger/hledger.m4.md

@@ -422,7 +422,6 @@ With the `-s`/`--strict` flag, additional checks are performed:
 - Are all commodities declared with a `commodity` directive ?
   ([Commodity error checking](#commodity-error-checking))
 - Are all commodity conversions declared explicitly ?
-- Are all commodity conversion equity postings occurring in adjacent pairs ?
 
 You can use the [check](#check) command to run individual checks -- the
 ones listed above and some more.

hledger/test/journal/costs.test

@@ -506,24 +506,7 @@ $ hledger -f- print --infer-costs
 
 >=0
 
-# 39. In strict mode, conversion postings must be in adjacent pairs.
+# 39. If a conversion pair matches several postings it should throw an error
-<
-account assets
-account equity:conversion
-account expenses:foreign currency
-commodity €0.
-commodity $0.
-2011/01/01
-    expenses:foreign currency            €100
-    equity:conversion                   €-100
-    assets                              $-135
-    equity:conversion                    $135
-
-$ hledger -f- print -s
->2 /Conversion postings must occur in adjacent pairs/
->=1
-
-# 40. If a conversion pair matches several postings it should throw an error
 <
 2011/01/01
     expenses:foreign currency    €100 @@ $135
@@ -537,7 +520,7 @@ $ hledger -f- print --infer-costs
 >2 /There is not a unique posting which matches the conversion posting pair/
 >=1
 
-# 41. If a conversion pair does not match it should throw an error
+# 42. If a conversion pair does not match it should throw an error
 <
 2011/01/01
     expenses:foreign currency            €120
@@ -551,7 +534,7 @@ $ hledger -f- print --infer-costs
 >2 /There is not a unique posting which matches the conversion posting pair/
 >=1
 
-# 42. Multiple conversion pairs which match a single posting should cause an
+# 43. Multiple conversion pairs which match a single posting should cause an
 # error, and should not match both ‘sides’ of the conversion
 <
 2011/01/01
@@ -567,7 +550,7 @@ $ hledger -f- print --infer-costs
 >2 /There is not a unique posting which matches the conversion posting pair/
 >=1
 
-# 43. We can combine ‘other’ amounts into one posting, if they still match up.
+# 44. We can combine ‘other’ amounts into one posting, if they still match up.
 <
 2011-01-01
     expenses:foreign currency    €100 @ $1.35