Implement sc-dictionary nodes masking to avoid large memory usages

[NikitaZotov]

Is your feature request related to a problem? Please describe. After #41 each node of sc-dictionary has 255 childs, some ones of that never appear. There is needed a mechanism to masking nodes so that use small memmory segments.

Describe the solution you'd like You can explicitly specify the ranges of those characters that can be stored in storage, and filter out others. You can also use bits in the mask to indicate the language of the text.