Fix completions in non Lua files
Stop removing period from word separators

It was originally necessary to remove period from the list of word
separators in order get completions of items with periods in them
working.  Now that we do all the completion logic ourselves this is no
longer needed (and it breaks some kinds of cursor movements so it's
bad).
Fixed completions in Sublime Text 3

Due to changes in the package structure in ST3 completions were broken.
 Also added a user preference called "corona_sdk_completion" which can
be set to false to switch off Corona SDK completion and use the default
Sublime Text "fuzzy" completion of strings in the source file.
Renamed 'CoronaSDK.sublime-build' to 'Corona SDK.sublime-build' so the name shows correctly in the menu

Apparently there isn't a directive in the .sublime-build file to set
the menu label like there is in other file types.
Improved completion list

Added a bunch of constants and object member functions to the
completion list to make it more complete (as it were).
Updated readme