Update README.md

Minor syntactical changes made.
Update README.md

Radio button code edited
Update README.md

How to install by using source code
Update RETableViewOptionsController.h
Update RETableViewOptionsController.m
handle selected item
The height of header and footer will be calculated correctly now when setting header or footer of a UITableViewSection via headerTitle or footerTitle.
Introduced user-interaction state for cells. Cells can now be enabled and disabled via the enabled property.
Fix RETableViewBoolCell constraints on iOS 8

On iOS 8 UIKit adds own constraints to contentView, so removing all
contentView’s constraints causes problems when the cell
is displayed for the second time on the screen.
Fix RETableViewSegmentedCell constraints on iOS 8

On iOS 8 UIKit adds own constraints to contentView, so removing all
contentView’s constraints causes problems when the cell
is displayed for the second time on the screen.
Fix possible NSRangeException in -tableView:canEditRowAtIndexPath:

On iOS 8 NSRangeException was being thrown after calling -removeItem: and then -reloadSectionWithAnimation:
The fix adds checks if section and row indices are within bounds.
Merge pull request #176 from max-horvath/footer-header-title-height-fix

The height of header and footer are calculated incorrectly
Merge pull request #179 from fastred/fix_nsrangeexception

Fix possible NSRangeException in -tableView:canEditRowAtIndexPath:
Merge pull request #177 from max-horvath/enable-disable-items

User-interaction state for cells (Enabled/Disable cells)
Version bump (1.5.11)
Merge pull request #178 from fastred/master

Fix RETableViewBoolCell's and RETableViewSegmentedCell's layout on iOS 8
Merge pull request #151 from bhavya-kothari/master

Minor changes to README.md
Merge pull request #173 from unixo/master

RETableViewOptionsController current selection
Update RETableViewBoolCell.m
Update RETableViewLongTextCell.m