Do not display comment thread by default

When the comment thread gets long it can be pretty distracting; you
expect to see issue details but instead of shown several screens of
text.

Comment thread can be displayed using the "--comments" option, like
this:

    $ issue show --comments <issue>

issue.py

@@ -1541,7 +1541,7 @@ def commandShow(ui):
             print('\n{}: {}\n'.format(closing_git_commit_heading, closing_git_commit))
 
         issue_comment_thread = dict((issue_data['comments'][key]['timestamp'], key) for key in issue_data['comments'])
-        if issue_comment_thread:
+        if issue_comment_thread and '--comments' in ui:
             comment_thread_heading = '---- COMMENT THREAD:'
             comment_thread_heading = colorise('white', comment_thread_heading)
             print('\n{}'.format(comment_thread_heading))

issue/__init__.py

@@ -9,4 +9,4 @@
 from . import objects
 
 
-__version__ = '0.2.11'
+__version__ = '0.2.12'

ui.json

@@ -524,7 +524,8 @@
             "doc": {
                 "help": "Show information about issues.",
                 "usage": [
-                    "show <sha1>"
+                    "show <issue>",
+                    "show --comments <issue>"
                 ]
             },
             "options": {
@@ -539,11 +540,19 @@
                         "short": "i",
                         "long": "index",
                         "help": "index selected issue before showing it"
+                    },
+                    {
+                        "short": "c",
+                        "long": "comments",
+                        "help": "show comment thread (if exists)"
                     }
                 ]
             },
             "commands": {
                 "log": {
+                    "doc": {
+                        "help": "Show history of an issue"
+                    },
                     "operands": {
                         "no": [1, 1],
                         "help": {