Update version number for 0.70 release.

Update version number for 0.69 release.

Update version number for 0.68 release.

This commit also updates the dumps of Plink's and PSCP's help output,
adding the -proxycmd option to both and the -shareexists option to
Plink.

(Or rather, _re_-adding the latter, since it was introduced in error
by commit 07af4ed due to a branch management error and hastily
removed again in 29e8c24. This time it really does match reality.)

p0.67-t029, as released

77aba7921cd8f91c0285edfc25f807f5b66e2cea3407db1c5a27fc6c3ce0b5c7 *plink.exe
86660866757ad827362c169b38403dfbce13ea62e79a3960cf829b6f9adbd339 *putty.7z
31ba5b51450e1b1fd2cc6038ceb107058068519e9535907ab06850ed23c989b3 *putty.exe

Update version number for 0.67 release.

p0.66-t028, as released

5952a9fbdf966237ce3a51e3b9d7acc754090211c91a17d83859cda4d6c6104f *plink.exe
218aadbb0664a25cffdedbd48f8404152ee287a87d53994c979bbf5c11601197 *putty.exe
e12b1da7804514f07348938ead7b582ec5c56a85503b023d6bc4fac877709ccf *putty.pdb.7z

p0.66-t027, as released

d19648bf98c48d5c81b6a8a4b5bbf777579fced11bd61fd58ba11c8b97fe3ca5 *putty.exe
e5a2127ebe1c253a95910103cb27331845de4bf9bd53a72c0a247e396fd02ce0 *putty.pdb

Update version number for 0.66 release.

p0.65-t026, as released.

51bb7302285d6f7f1310f10fa3b9a5695111a29d210dc87d67f7c7b982c0d5d9 *putty.exe
d7b9e04387d8e99e321932737c9d4b14d2bf2226791a6e0a69479e32bae5b4b3 *putty.pdb.7z

p0.65-t025, as released

8d1bdc7d3e057c8517b3163083bd836cd89a3598f3dea1d800a0b6569f1adce6 *putty.exe
8e7725351f7e956a1efd84d1c9c646066dd6decbbeba97bfd78fef686f39583f *putty.pdb.7z