hidePasswords, preferences, UI improvements.

[ADDED]     hidePasswords to Mac app for hiding the passwords in the large passwords display, hold alt to reveal.
[ADDED]     Way to easily open the Mac app's preferences.
[IMPROVED]  Use transparent main window to improve the blur effect.
[ADDED]     Key equivalent coach marks when holding alt.
[FIXED]     Don't change sites table when site text field loses focus.

Site/2013-05/security.html

@@ -359,7 +359,7 @@
                         <p><h2 class="inline">Custom passwords</h2>
                         are sometimes still a necessity.  You may want to store a password you've been using for a long time in your manager, or your boss may have set an unchangable password on your computer for you to use.  Since Master Password's passwords are a mathematical result of your unchanging master password, it is impossible for it to be used with passwords that are created via another way.</p>
                         <p>The Master Password application however <em>functions as a hybrid password manager, implementing both the Master Password algorithm and a vault-like password solution</em>.  In the second mode, Master Password uses your master key to encrypt custom passwords and store the encrypted result in a vault.  Since we use the master key for this process, the result is a vault that is much harder to break into than that used by many other vault-based password solutions (specifically
-                        because the encryption key is a 64-byte key derived from your master pasword using scrypt key derivation).  As a result, <strong>this trade-off has been mitigated</strong>.</p>
+                        because the encryption key is a large key derived from your master pasword using scrypt key derivation).  As a result, <strong>this trade-off has been mitigated</strong>.</p>
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