revise check_errors_conv.py to match mezcla style

[tomasohara]

Please make sure check_errors_conv.py better matches mezcla's style.

1. Don't comment out code without indicating why
2. Use ## to indicate temporary comments (e.g., old code)
3. Use python-lint (n.b., religiously)
4. Add shebang line (review template.py)
5. Review my email for frequently made requests

$ python-lint check_errors_conv.py | cat
************* Module aviyan-shell-scripts.check_errors_conv
check_errors_conv.py:439:0: C0304: Final newline missing (missing-final-newline)
check_errors_conv.py:96:0: C0116: Missing function or method docstring (missing-function-docstring)
check_errors_conv.py:99:4: W0621: Redefining name 'non_option_args' from outer scope (line 427) (redefined-outer-name)
check_errors_conv.py:150:4: W0601: Global variable 'show_warnings' undefined at the module level (global-variable-undefined)
check_errors_conv.py:150:4: W0601: Global variable 'show_informative' undefined at the module level (global-variable-undefined)
check_errors_conv.py:150:4: W0601: Global variable 'asterisks' undefined at the module level (global-variable-undefined)
check_errors_conv.py:161:0: C0116: Missing function or method docstring (missing-function-docstring)
check_errors_conv.py:187:0: C0116: Missing function or method docstring (missing-function-docstring)
check_errors_conv.py:190:0: C0116: Missing function or method docstring (missing-function-docstring)
check_errors_conv.py:194:0: C0116: Missing function or method docstring (missing-function-docstring)
check_errors_conv.py:214:0: C0116: Missing function or method docstring (missing-function-docstring)
check_errors_conv.py:218:0: C0116: Missing function or method docstring (missing-function-docstring)
check_errors_conv.py:225:0: C0116: Missing function or method docstring (missing-function-docstring)
check_errors_conv.py:238:0: C0116: Missing function or method docstring (missing-function-docstring)
check_errors_conv.py:238:35: W0621: Redefining name 'relaxed' from outer scope (line 73) (redefined-outer-name)
check_errors_conv.py:268:0: C0116: Missing function or method docstring (missing-function-docstring)
check_errors_conv.py:269:4: W0601: Global variable 'current_file' undefined at the module level (global-variable-undefined)
check_errors_conv.py:269:4: W0601: Global variable 'before_context' undefined at the module level (global-variable-undefined)
check_errors_conv.py:270:31: E0606: Possibly using variable 'non_option_args' before assignment (possibly-used-before-assignment)
check_errors_conv.py:279:19: W0718: Catching too general exception Exception (broad-exception-caught)
check_errors_conv.py:288:15: W0718: Catching too general exception Exception (broad-exception-caught)
check_errors_conv.py:271:8: W0612: Unused variable 'file_idx' (unused-variable)
check_errors_conv.py:49:4: W0611: Unused import common (unused-import)


$ git-stat
issuing: git status 
On branch aviyan/perl-to-py

[tomasohara]

See tomasohara/mezcla#131.