pgsql: libpq: URI parsing fixes

libpq: URI parsing fixes

Drop special handling of host component with slashes to mean
Unix-domain socket.  Specify it as separate parameter or using
percent-encoding now.

Allow omitting username, password, and port even if the corresponding
designators are present in URI.

Handle percent-encoding in query parameter keywords.

Alex Shulgin

some documentation improvements by myself

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/2d612abd4d330cd9d3f5a3f5936b20a6e837a69c

Modified Files
--------------
doc/src/sgml/libpq.sgml                |  219 ++++++++++++++++-------------
src/interfaces/libpq/fe-connect.c      |  242 ++++++++++++++------------------
src/interfaces/libpq/test/expected.out |   48 +++++--
src/interfaces/libpq/test/regress.in   |   16 ++-
4 files changed, 269 insertions(+), 256 deletions(-)