Initial changes for Shard-Query custom functions.  Many tests fail, will investigate
Fix most bugs - only one issue remains
Add example for custom funcs
ADD: a new function remove_custom_function
CHG: the function isCustomFunction uses isset() now, which could be
faster than in_array()
CHG: the function isReserved() had a wrong reference to "self"
CHG: the processing of * doesn't need a custom function (I think), I
have removed the access to isCustomFunction()
ADD: the custom function is in the first loop a colref, the next loop
handles the parentheses, and the processor should correct the previous
token from colref to function. I have added code to check the colref
against the customFunctions array.
ADD: a new function, which allows the user to remove custom functions
from the parser (the user can re-use the parser object)
CHG: the test case has been finished and it eturns "ok"
Change new functions to camelCase
Merge branch customfuncs