Fix error that allowed VACUUM to remove ctid chains too soon, and add more checking in code that follows ctid links

This fixes a long-standing problem that could cause crashes in very rare circumstances.

Fix CHAR() to properly pad spaces to the specified length when using a multiple-byte character set (Yoshiyuki Asaba)

In prior releases, the padding of CHAR() was incorrect because it only padded to the specified number of bytes without considering how many characters were stored.

Fix missing rows in queries like UPDATE a=... WHERE a... with GiST index on column a

Improve checking for partially-written WAL pages

Improve robustness of signal handling when SSL is enabled

Various memory leakage fixes

Various portability improvements

Fix PL/pgSQL to handle var := var correctly when the variable is of pass-by-reference type