Avoid confusable characters

[waldyrious]

• 1 (one), I (uppercase i), l (lowercase L), | (pipe)
• 0 (zero), O (uppercase o)
•  (space)
• ' (straight apostrophe), ’ (curly apostrophe), ` (backtick), ´ (acute accent)
• " (double quotes), '' (two single quotes), “/” (curly quotes

[waldyrious]

Note: if we were to use a lower threshold for number-letter confusability (e.g. to support handwritten passwords), we'd be restricted to a very small subset of digits, as we'd rule out (besides 0 and 1 mentioned above):

• 2/Z
• 5/S
• 6/G
• 8/B
• 9/g

leaving us with only 3, 4 and 7, which would defeat the purpose of including this class of symbols anyway.

[waldyrious]

Note: Flickr doesn't accept leading spaces in passwords.